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// jpgd.cpp - C++ class for JPEG decompression. Written by Richard Geldreich <richgel99@gmail.com> between 1994-2020.
// Supports progressive and baseline sequential JPEG image files, and the most common chroma subsampling factors: Y, H1V1, H2V1, H1V2, and H2V2.
// Supports box and linear chroma upsampling.
//
// Released under two licenses. You are free to choose which license you want:
// License 1:
// Public Domain
//
// License 2:
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Alex Evans: Linear memory allocator (taken from jpge.h).
// v1.04, May. 19, 2012: Code tweaks to fix VS2008 static code analysis warnings
// v2.00, March 20, 2020: Fuzzed with zzuf and afl. Fixed several issues, converted most assert()'s to run-time checks. Added chroma upsampling. Removed freq. domain upsampling. gcc/clang warnings.
//
#ifdef _MSC_VER
#ifndef BASISU_NO_ITERATOR_DEBUG_LEVEL
#if defined(_DEBUG) || defined(DEBUG)
#define _ITERATOR_DEBUG_LEVEL 1
#define _SECURE_SCL 1
#else
#define _SECURE_SCL 0
#define _ITERATOR_DEBUG_LEVEL 0
#endif
#endif
#endif
#include "jpgd.h"
#include <string.h>
#include <algorithm>
#include <assert.h>
#ifdef _MSC_VER
#pragma warning (disable : 4611) // warning C4611: interaction between '_setjmp' and C++ object destruction is non-portable
#endif
#define JPGD_TRUE (1)
#define JPGD_FALSE (0)
#define JPGD_MAX(a,b) (((a)>(b)) ? (a) : (b))
#define JPGD_MIN(a,b) (((a)<(b)) ? (a) : (b))
namespace jpgd {
static inline void* jpgd_malloc(size_t nSize) { return malloc(nSize); }
static inline void jpgd_free(void* p) { free(p); }
// DCT coefficients are stored in this sequence.
static int g_ZAG[64] = { 0,1,8,16,9,2,3,10,17,24,32,25,18,11,4,5,12,19,26,33,40,48,41,34,27,20,13,6,7,14,21,28,35,42,49,56,57,50,43,36,29,22,15,23,30,37,44,51,58,59,52,45,38,31,39,46,53,60,61,54,47,55,62,63 };
enum JPEG_MARKER
{
M_SOF0 = 0xC0, M_SOF1 = 0xC1, M_SOF2 = 0xC2, M_SOF3 = 0xC3, M_SOF5 = 0xC5, M_SOF6 = 0xC6, M_SOF7 = 0xC7, M_JPG = 0xC8,
M_SOF9 = 0xC9, M_SOF10 = 0xCA, M_SOF11 = 0xCB, M_SOF13 = 0xCD, M_SOF14 = 0xCE, M_SOF15 = 0xCF, M_DHT = 0xC4, M_DAC = 0xCC,
M_RST0 = 0xD0, M_RST1 = 0xD1, M_RST2 = 0xD2, M_RST3 = 0xD3, M_RST4 = 0xD4, M_RST5 = 0xD5, M_RST6 = 0xD6, M_RST7 = 0xD7,
M_SOI = 0xD8, M_EOI = 0xD9, M_SOS = 0xDA, M_DQT = 0xDB, M_DNL = 0xDC, M_DRI = 0xDD, M_DHP = 0xDE, M_EXP = 0xDF,
M_APP0 = 0xE0, M_APP15 = 0xEF, M_JPG0 = 0xF0, M_JPG13 = 0xFD, M_COM = 0xFE, M_TEM = 0x01, M_ERROR = 0x100, RST0 = 0xD0
};
enum JPEG_SUBSAMPLING { JPGD_GRAYSCALE = 0, JPGD_YH1V1, JPGD_YH2V1, JPGD_YH1V2, JPGD_YH2V2 };
#define CONST_BITS 13
#define PASS1_BITS 2
#define SCALEDONE ((int32)1)
#define FIX_0_298631336 ((int32)2446) /* FIX(0.298631336) */
#define FIX_0_390180644 ((int32)3196) /* FIX(0.390180644) */
#define FIX_0_541196100 ((int32)4433) /* FIX(0.541196100) */
#define FIX_0_765366865 ((int32)6270) /* FIX(0.765366865) */
#define FIX_0_899976223 ((int32)7373) /* FIX(0.899976223) */
#define FIX_1_175875602 ((int32)9633) /* FIX(1.175875602) */
#define FIX_1_501321110 ((int32)12299) /* FIX(1.501321110) */
#define FIX_1_847759065 ((int32)15137) /* FIX(1.847759065) */
#define FIX_1_961570560 ((int32)16069) /* FIX(1.961570560) */
#define FIX_2_053119869 ((int32)16819) /* FIX(2.053119869) */
#define FIX_2_562915447 ((int32)20995) /* FIX(2.562915447) */
#define FIX_3_072711026 ((int32)25172) /* FIX(3.072711026) */
#define DESCALE(x,n) (((x) + (SCALEDONE << ((n)-1))) >> (n))
#define DESCALE_ZEROSHIFT(x,n) (((x) + (128 << (n)) + (SCALEDONE << ((n)-1))) >> (n))
#define MULTIPLY(var, cnst) ((var) * (cnst))
#define CLAMP(i) ((static_cast<uint>(i) > 255) ? (((~i) >> 31) & 0xFF) : (i))
static inline int left_shifti(int val, uint32_t bits)
{
return static_cast<int>(static_cast<uint32_t>(val) << bits);
}
// Compiler creates a fast path 1D IDCT for X non-zero columns
template <int NONZERO_COLS>
struct Row
{
static void idct(int* pTemp, const jpgd_block_t* pSrc)
{
// ACCESS_COL() will be optimized at compile time to either an array access, or 0. Good compilers will then optimize out muls against 0.
#define ACCESS_COL(x) (((x) < NONZERO_COLS) ? (int)pSrc[x] : 0)
const int z2 = ACCESS_COL(2), z3 = ACCESS_COL(6);
const int z1 = MULTIPLY(z2 + z3, FIX_0_541196100);
const int tmp2 = z1 + MULTIPLY(z3, -FIX_1_847759065);
const int tmp3 = z1 + MULTIPLY(z2, FIX_0_765366865);
const int tmp0 = left_shifti(ACCESS_COL(0) + ACCESS_COL(4), CONST_BITS);
const int tmp1 = left_shifti(ACCESS_COL(0) - ACCESS_COL(4), CONST_BITS);
const int tmp10 = tmp0 + tmp3, tmp13 = tmp0 - tmp3, tmp11 = tmp1 + tmp2, tmp12 = tmp1 - tmp2;
const int atmp0 = ACCESS_COL(7), atmp1 = ACCESS_COL(5), atmp2 = ACCESS_COL(3), atmp3 = ACCESS_COL(1);
const int bz1 = atmp0 + atmp3, bz2 = atmp1 + atmp2, bz3 = atmp0 + atmp2, bz4 = atmp1 + atmp3;
const int bz5 = MULTIPLY(bz3 + bz4, FIX_1_175875602);
const int az1 = MULTIPLY(bz1, -FIX_0_899976223);
const int az2 = MULTIPLY(bz2, -FIX_2_562915447);
const int az3 = MULTIPLY(bz3, -FIX_1_961570560) + bz5;
const int az4 = MULTIPLY(bz4, -FIX_0_390180644) + bz5;
const int btmp0 = MULTIPLY(atmp0, FIX_0_298631336) + az1 + az3;
const int btmp1 = MULTIPLY(atmp1, FIX_2_053119869) + az2 + az4;
const int btmp2 = MULTIPLY(atmp2, FIX_3_072711026) + az2 + az3;
const int btmp3 = MULTIPLY(atmp3, FIX_1_501321110) + az1 + az4;
pTemp[0] = DESCALE(tmp10 + btmp3, CONST_BITS - PASS1_BITS);
pTemp[7] = DESCALE(tmp10 - btmp3, CONST_BITS - PASS1_BITS);
pTemp[1] = DESCALE(tmp11 + btmp2, CONST_BITS - PASS1_BITS);
pTemp[6] = DESCALE(tmp11 - btmp2, CONST_BITS - PASS1_BITS);
pTemp[2] = DESCALE(tmp12 + btmp1, CONST_BITS - PASS1_BITS);
pTemp[5] = DESCALE(tmp12 - btmp1, CONST_BITS - PASS1_BITS);
pTemp[3] = DESCALE(tmp13 + btmp0, CONST_BITS - PASS1_BITS);
pTemp[4] = DESCALE(tmp13 - btmp0, CONST_BITS - PASS1_BITS);
}
};
template <>
struct Row<0>
{
static void idct(int* pTemp, const jpgd_block_t* pSrc)
{
(void)pTemp;
(void)pSrc;
}
};
template <>
struct Row<1>
{
static void idct(int* pTemp, const jpgd_block_t* pSrc)
{
const int dcval = left_shifti(pSrc[0], PASS1_BITS);
pTemp[0] = dcval;
pTemp[1] = dcval;
pTemp[2] = dcval;
pTemp[3] = dcval;
pTemp[4] = dcval;
pTemp[5] = dcval;
pTemp[6] = dcval;
pTemp[7] = dcval;
}
};
// Compiler creates a fast path 1D IDCT for X non-zero rows
template <int NONZERO_ROWS>
struct Col
{
static void idct(uint8* pDst_ptr, const int* pTemp)
{
// ACCESS_ROW() will be optimized at compile time to either an array access, or 0.
#define ACCESS_ROW(x) (((x) < NONZERO_ROWS) ? pTemp[x * 8] : 0)
const int z2 = ACCESS_ROW(2);
const int z3 = ACCESS_ROW(6);
const int z1 = MULTIPLY(z2 + z3, FIX_0_541196100);
const int tmp2 = z1 + MULTIPLY(z3, -FIX_1_847759065);
const int tmp3 = z1 + MULTIPLY(z2, FIX_0_765366865);
const int tmp0 = left_shifti(ACCESS_ROW(0) + ACCESS_ROW(4), CONST_BITS);
const int tmp1 = left_shifti(ACCESS_ROW(0) - ACCESS_ROW(4), CONST_BITS);
const int tmp10 = tmp0 + tmp3, tmp13 = tmp0 - tmp3, tmp11 = tmp1 + tmp2, tmp12 = tmp1 - tmp2;
const int atmp0 = ACCESS_ROW(7), atmp1 = ACCESS_ROW(5), atmp2 = ACCESS_ROW(3), atmp3 = ACCESS_ROW(1);
const int bz1 = atmp0 + atmp3, bz2 = atmp1 + atmp2, bz3 = atmp0 + atmp2, bz4 = atmp1 + atmp3;
const int bz5 = MULTIPLY(bz3 + bz4, FIX_1_175875602);
const int az1 = MULTIPLY(bz1, -FIX_0_899976223);
const int az2 = MULTIPLY(bz2, -FIX_2_562915447);
const int az3 = MULTIPLY(bz3, -FIX_1_961570560) + bz5;
const int az4 = MULTIPLY(bz4, -FIX_0_390180644) + bz5;
const int btmp0 = MULTIPLY(atmp0, FIX_0_298631336) + az1 + az3;
const int btmp1 = MULTIPLY(atmp1, FIX_2_053119869) + az2 + az4;
const int btmp2 = MULTIPLY(atmp2, FIX_3_072711026) + az2 + az3;
const int btmp3 = MULTIPLY(atmp3, FIX_1_501321110) + az1 + az4;
int i = DESCALE_ZEROSHIFT(tmp10 + btmp3, CONST_BITS + PASS1_BITS + 3);
pDst_ptr[8 * 0] = (uint8)CLAMP(i);
i = DESCALE_ZEROSHIFT(tmp10 - btmp3, CONST_BITS + PASS1_BITS + 3);
pDst_ptr[8 * 7] = (uint8)CLAMP(i);
i = DESCALE_ZEROSHIFT(tmp11 + btmp2, CONST_BITS + PASS1_BITS + 3);
pDst_ptr[8 * 1] = (uint8)CLAMP(i);
i = DESCALE_ZEROSHIFT(tmp11 - btmp2, CONST_BITS + PASS1_BITS + 3);
pDst_ptr[8 * 6] = (uint8)CLAMP(i);
i = DESCALE_ZEROSHIFT(tmp12 + btmp1, CONST_BITS + PASS1_BITS + 3);
pDst_ptr[8 * 2] = (uint8)CLAMP(i);
i = DESCALE_ZEROSHIFT(tmp12 - btmp1, CONST_BITS + PASS1_BITS + 3);
pDst_ptr[8 * 5] = (uint8)CLAMP(i);
i = DESCALE_ZEROSHIFT(tmp13 + btmp0, CONST_BITS + PASS1_BITS + 3);
pDst_ptr[8 * 3] = (uint8)CLAMP(i);
i = DESCALE_ZEROSHIFT(tmp13 - btmp0, CONST_BITS + PASS1_BITS + 3);
pDst_ptr[8 * 4] = (uint8)CLAMP(i);
}
};
template <>
struct Col<1>
{
static void idct(uint8* pDst_ptr, const int* pTemp)
{
int dcval = DESCALE_ZEROSHIFT(pTemp[0], PASS1_BITS + 3);
const uint8 dcval_clamped = (uint8)CLAMP(dcval);
pDst_ptr[0 * 8] = dcval_clamped;
pDst_ptr[1 * 8] = dcval_clamped;
pDst_ptr[2 * 8] = dcval_clamped;
pDst_ptr[3 * 8] = dcval_clamped;
pDst_ptr[4 * 8] = dcval_clamped;
pDst_ptr[5 * 8] = dcval_clamped;
pDst_ptr[6 * 8] = dcval_clamped;
pDst_ptr[7 * 8] = dcval_clamped;
}
};
static const uint8 s_idct_row_table[] =
{
1,0,0,0,0,0,0,0, 2,0,0,0,0,0,0,0, 2,1,0,0,0,0,0,0, 2,1,1,0,0,0,0,0, 2,2,1,0,0,0,0,0, 3,2,1,0,0,0,0,0, 4,2,1,0,0,0,0,0, 4,3,1,0,0,0,0,0,
4,3,2,0,0,0,0,0, 4,3,2,1,0,0,0,0, 4,3,2,1,1,0,0,0, 4,3,2,2,1,0,0,0, 4,3,3,2,1,0,0,0, 4,4,3,2,1,0,0,0, 5,4,3,2,1,0,0,0, 6,4,3,2,1,0,0,0,
6,5,3,2,1,0,0,0, 6,5,4,2,1,0,0,0, 6,5,4,3,1,0,0,0, 6,5,4,3,2,0,0,0, 6,5,4,3,2,1,0,0, 6,5,4,3,2,1,1,0, 6,5,4,3,2,2,1,0, 6,5,4,3,3,2,1,0,
6,5,4,4,3,2,1,0, 6,5,5,4,3,2,1,0, 6,6,5,4,3,2,1,0, 7,6,5,4,3,2,1,0, 8,6,5,4,3,2,1,0, 8,7,5,4,3,2,1,0, 8,7,6,4,3,2,1,0, 8,7,6,5,3,2,1,0,
8,7,6,5,4,2,1,0, 8,7,6,5,4,3,1,0, 8,7,6,5,4,3,2,0, 8,7,6,5,4,3,2,1, 8,7,6,5,4,3,2,2, 8,7,6,5,4,3,3,2, 8,7,6,5,4,4,3,2, 8,7,6,5,5,4,3,2,
8,7,6,6,5,4,3,2, 8,7,7,6,5,4,3,2, 8,8,7,6,5,4,3,2, 8,8,8,6,5,4,3,2, 8,8,8,7,5,4,3,2, 8,8,8,7,6,4,3,2, 8,8,8,7,6,5,3,2, 8,8,8,7,6,5,4,2,
8,8,8,7,6,5,4,3, 8,8,8,7,6,5,4,4, 8,8,8,7,6,5,5,4, 8,8,8,7,6,6,5,4, 8,8,8,7,7,6,5,4, 8,8,8,8,7,6,5,4, 8,8,8,8,8,6,5,4, 8,8,8,8,8,7,5,4,
8,8,8,8,8,7,6,4, 8,8,8,8,8,7,6,5, 8,8,8,8,8,7,6,6, 8,8,8,8,8,7,7,6, 8,8,8,8,8,8,7,6, 8,8,8,8,8,8,8,6, 8,8,8,8,8,8,8,7, 8,8,8,8,8,8,8,8,
};
static const uint8 s_idct_col_table[] =
{
1, 1, 2, 3, 3, 3, 3, 3, 3, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8
};
// Scalar "fast pathing" IDCT.
static void idct(const jpgd_block_t* pSrc_ptr, uint8* pDst_ptr, int block_max_zag)
{
assert(block_max_zag >= 1);
assert(block_max_zag <= 64);
if (block_max_zag <= 1)
{
int k = ((pSrc_ptr[0] + 4) >> 3) + 128;
k = CLAMP(k);
k = k | (k << 8);
k = k | (k << 16);
for (int i = 8; i > 0; i--)
{
*(int*)&pDst_ptr[0] = k;
*(int*)&pDst_ptr[4] = k;
pDst_ptr += 8;
}
return;
}
int temp[64];
const jpgd_block_t* pSrc = pSrc_ptr;
int* pTemp = temp;
const uint8* pRow_tab = &s_idct_row_table[(block_max_zag - 1) * 8];
int i;
for (i = 8; i > 0; i--, pRow_tab++)
{
switch (*pRow_tab)
{
case 0: Row<0>::idct(pTemp, pSrc); break;
case 1: Row<1>::idct(pTemp, pSrc); break;
case 2: Row<2>::idct(pTemp, pSrc); break;
case 3: Row<3>::idct(pTemp, pSrc); break;
case 4: Row<4>::idct(pTemp, pSrc); break;
case 5: Row<5>::idct(pTemp, pSrc); break;
case 6: Row<6>::idct(pTemp, pSrc); break;
case 7: Row<7>::idct(pTemp, pSrc); break;
case 8: Row<8>::idct(pTemp, pSrc); break;
}
pSrc += 8;
pTemp += 8;
}
pTemp = temp;
const int nonzero_rows = s_idct_col_table[block_max_zag - 1];
for (i = 8; i > 0; i--)
{
switch (nonzero_rows)
{
case 1: Col<1>::idct(pDst_ptr, pTemp); break;
case 2: Col<2>::idct(pDst_ptr, pTemp); break;
case 3: Col<3>::idct(pDst_ptr, pTemp); break;
case 4: Col<4>::idct(pDst_ptr, pTemp); break;
case 5: Col<5>::idct(pDst_ptr, pTemp); break;
case 6: Col<6>::idct(pDst_ptr, pTemp); break;
case 7: Col<7>::idct(pDst_ptr, pTemp); break;
case 8: Col<8>::idct(pDst_ptr, pTemp); break;
}
pTemp++;
pDst_ptr++;
}
}
// Retrieve one character from the input stream.
inline uint jpeg_decoder::get_char()
{
// Any bytes remaining in buffer?
if (!m_in_buf_left)
{
// Try to get more bytes.
prep_in_buffer();
// Still nothing to get?
if (!m_in_buf_left)
{
// Pad the end of the stream with 0xFF 0xD9 (EOI marker)
int t = m_tem_flag;
m_tem_flag ^= 1;
if (t)
return 0xD9;
else
return 0xFF;
}
}
uint c = *m_pIn_buf_ofs++;
m_in_buf_left--;
return c;
}
// Same as previous method, except can indicate if the character is a pad character or not.
inline uint jpeg_decoder::get_char(bool* pPadding_flag)
{
if (!m_in_buf_left)
{
prep_in_buffer();
if (!m_in_buf_left)
{
*pPadding_flag = true;
int t = m_tem_flag;
m_tem_flag ^= 1;
if (t)
return 0xD9;
else
return 0xFF;
}
}
*pPadding_flag = false;
uint c = *m_pIn_buf_ofs++;
m_in_buf_left--;
return c;
}
// Inserts a previously retrieved character back into the input buffer.
inline void jpeg_decoder::stuff_char(uint8 q)
{
// This could write before the input buffer, but we've placed another array there.
*(--m_pIn_buf_ofs) = q;
m_in_buf_left++;
}
// Retrieves one character from the input stream, but does not read past markers. Will continue to return 0xFF when a marker is encountered.
inline uint8 jpeg_decoder::get_octet()
{
bool padding_flag;
int c = get_char(&padding_flag);
if (c == 0xFF)
{
if (padding_flag)
return 0xFF;
c = get_char(&padding_flag);
if (padding_flag)
{
stuff_char(0xFF);
return 0xFF;
}
if (c == 0x00)
return 0xFF;
else
{
stuff_char(static_cast<uint8>(c));
stuff_char(0xFF);
return 0xFF;
}
}
return static_cast<uint8>(c);
}
// Retrieves a variable number of bits from the input stream. Does not recognize markers.
inline uint jpeg_decoder::get_bits(int num_bits)
{
if (!num_bits)
return 0;
uint i = m_bit_buf >> (32 - num_bits);
if ((m_bits_left -= num_bits) <= 0)
{
m_bit_buf <<= (num_bits += m_bits_left);
uint c1 = get_char();
uint c2 = get_char();
m_bit_buf = (m_bit_buf & 0xFFFF0000) | (c1 << 8) | c2;
m_bit_buf <<= -m_bits_left;
m_bits_left += 16;
assert(m_bits_left >= 0);
}
else
m_bit_buf <<= num_bits;
return i;
}
// Retrieves a variable number of bits from the input stream. Markers will not be read into the input bit buffer. Instead, an infinite number of all 1's will be returned when a marker is encountered.
inline uint jpeg_decoder::get_bits_no_markers(int num_bits)
{
if (!num_bits)
return 0;
assert(num_bits <= 16);
uint i = m_bit_buf >> (32 - num_bits);
if ((m_bits_left -= num_bits) <= 0)
{
m_bit_buf <<= (num_bits += m_bits_left);
if ((m_in_buf_left < 2) || (m_pIn_buf_ofs[0] == 0xFF) || (m_pIn_buf_ofs[1] == 0xFF))
{
uint c1 = get_octet();
uint c2 = get_octet();
m_bit_buf |= (c1 << 8) | c2;
}
else
{
m_bit_buf |= ((uint)m_pIn_buf_ofs[0] << 8) | m_pIn_buf_ofs[1];
m_in_buf_left -= 2;
m_pIn_buf_ofs += 2;
}
m_bit_buf <<= -m_bits_left;
m_bits_left += 16;
assert(m_bits_left >= 0);
}
else
m_bit_buf <<= num_bits;
return i;
}
// Decodes a Huffman encoded symbol.
inline int jpeg_decoder::huff_decode(huff_tables* pH)
{
if (!pH)
stop_decoding(JPGD_DECODE_ERROR);
int symbol;
// Check first 8-bits: do we have a complete symbol?
if ((symbol = pH->look_up[m_bit_buf >> 24]) < 0)
{
// Decode more bits, use a tree traversal to find symbol.
int ofs = 23;
do
{
unsigned int idx = -(int)(symbol + ((m_bit_buf >> ofs) & 1));
// This should never happen, but to be safe I'm turning these asserts into a run-time check.
if ((idx >= JPGD_HUFF_TREE_MAX_LENGTH) || (ofs < 0))
stop_decoding(JPGD_DECODE_ERROR);
symbol = pH->tree[idx];
ofs--;
} while (symbol < 0);
get_bits_no_markers(8 + (23 - ofs));
}
else
{
assert(symbol < JPGD_HUFF_CODE_SIZE_MAX_LENGTH);
get_bits_no_markers(pH->code_size[symbol]);
}
return symbol;
}
// Decodes a Huffman encoded symbol.
inline int jpeg_decoder::huff_decode(huff_tables* pH, int& extra_bits)
{
int symbol;
if (!pH)
stop_decoding(JPGD_DECODE_ERROR);
// Check first 8-bits: do we have a complete symbol?
if ((symbol = pH->look_up2[m_bit_buf >> 24]) < 0)
{
// Use a tree traversal to find symbol.
int ofs = 23;
do
{
unsigned int idx = -(int)(symbol + ((m_bit_buf >> ofs) & 1));
// This should never happen, but to be safe I'm turning these asserts into a run-time check.
if ((idx >= JPGD_HUFF_TREE_MAX_LENGTH) || (ofs < 0))
stop_decoding(JPGD_DECODE_ERROR);
symbol = pH->tree[idx];
ofs--;
} while (symbol < 0);
get_bits_no_markers(8 + (23 - ofs));
extra_bits = get_bits_no_markers(symbol & 0xF);
}
else
{
if (symbol & 0x8000)
{
//get_bits_no_markers((symbol >> 8) & 31);
assert(((symbol >> 8) & 31) <= 15);
get_bits_no_markers((symbol >> 8) & 15);
extra_bits = symbol >> 16;
}
else
{
int code_size = (symbol >> 8) & 31;
int num_extra_bits = symbol & 0xF;
int bits = code_size + num_extra_bits;
if (bits <= 16)
extra_bits = get_bits_no_markers(bits) & ((1 << num_extra_bits) - 1);
else
{
get_bits_no_markers(code_size);
extra_bits = get_bits_no_markers(num_extra_bits);
}
}
symbol &= 0xFF;
}
return symbol;
}
// Tables and macro used to fully decode the DPCM differences.
static const int s_extend_test[16] = { 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080, 0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 };
static const int s_extend_offset[16] = { 0, -1, -3, -7, -15, -31, -63, -127, -255, -511, -1023, -2047, -4095, -8191, -16383, -32767 };
//static const int s_extend_mask[] = { 0, (1 << 0), (1 << 1), (1 << 2), (1 << 3), (1 << 4), (1 << 5), (1 << 6), (1 << 7), (1 << 8), (1 << 9), (1 << 10), (1 << 11), (1 << 12), (1 << 13), (1 << 14), (1 << 15), (1 << 16) };
#define JPGD_HUFF_EXTEND(x, s) (((x) < s_extend_test[s & 15]) ? ((x) + s_extend_offset[s & 15]) : (x))
// Unconditionally frees all allocated m_blocks.
void jpeg_decoder::free_all_blocks()
{
m_pStream = nullptr;
for (mem_block* b = m_pMem_blocks; b; )
{
mem_block* n = b->m_pNext;
jpgd_free(b);
b = n;
}
m_pMem_blocks = nullptr;
}
// This method handles all errors. It will never return.
// It could easily be changed to use C++ exceptions.
JPGD_NORETURN void jpeg_decoder::stop_decoding(jpgd_status status)
{
m_error_code = status;
free_all_blocks();
longjmp(m_jmp_state, status);
}
void* jpeg_decoder::alloc(size_t nSize, bool zero)
{
nSize = (JPGD_MAX(nSize, 1) + 3) & ~3;
char* rv = nullptr;
for (mem_block* b = m_pMem_blocks; b; b = b->m_pNext)
{
if ((b->m_used_count + nSize) <= b->m_size)
{
rv = b->m_data + b->m_used_count;
b->m_used_count += nSize;
break;
}
}
if (!rv)
{
int capacity = JPGD_MAX(32768 - 256, ((int)nSize + 2047) & ~2047);
mem_block* b = (mem_block*)jpgd_malloc(sizeof(mem_block) + capacity);
if (!b)
{
stop_decoding(JPGD_NOTENOUGHMEM);
}
b->m_pNext = m_pMem_blocks;
m_pMem_blocks = b;
b->m_used_count = nSize;
b->m_size = capacity;
rv = b->m_data;
}
if (zero) memset(rv, 0, nSize);
return rv;
}
void jpeg_decoder::word_clear(void* p, uint16 c, uint n)
{
uint8* pD = (uint8*)p;
const uint8 l = c & 0xFF, h = (c >> 8) & 0xFF;
while (n)
{
pD[0] = l;
pD[1] = h;
pD += 2;
n--;
}
}
// Refill the input buffer.
// This method will sit in a loop until (A) the buffer is full or (B)
// the stream's read() method reports and end of file condition.
void jpeg_decoder::prep_in_buffer()
{
m_in_buf_left = 0;
m_pIn_buf_ofs = m_in_buf;
if (m_eof_flag)
return;
do
{
int bytes_read = m_pStream->read(m_in_buf + m_in_buf_left, JPGD_IN_BUF_SIZE - m_in_buf_left, &m_eof_flag);
if (bytes_read == -1)
stop_decoding(JPGD_STREAM_READ);
m_in_buf_left += bytes_read;
} while ((m_in_buf_left < JPGD_IN_BUF_SIZE) && (!m_eof_flag));
m_total_bytes_read += m_in_buf_left;
// Pad the end of the block with M_EOI (prevents the decompressor from going off the rails if the stream is invalid).
// (This dates way back to when this decompressor was written in C/asm, and the all-asm Huffman decoder did some fancy things to increase perf.)
word_clear(m_pIn_buf_ofs + m_in_buf_left, 0xD9FF, 64);
}
// Read a Huffman code table.
void jpeg_decoder::read_dht_marker()
{
int i, index, count;
uint8 huff_num[17];
uint8 huff_val[256];
uint num_left = get_bits(16);
if (num_left < 2)
stop_decoding(JPGD_BAD_DHT_MARKER);
num_left -= 2;
while (num_left)
{
index = get_bits(8);
huff_num[0] = 0;
count = 0;
for (i = 1; i <= 16; i++)
{
huff_num[i] = static_cast<uint8>(get_bits(8));
count += huff_num[i];
}
if (count > 255)
stop_decoding(JPGD_BAD_DHT_COUNTS);
bool symbol_present[256];
memset(symbol_present, 0, sizeof(symbol_present));
for (i = 0; i < count; i++)
{
const int s = get_bits(8);
// Check for obviously bogus tables.
if (symbol_present[s])
stop_decoding(JPGD_BAD_DHT_COUNTS);
huff_val[i] = static_cast<uint8_t>(s);
symbol_present[s] = true;
}
i = 1 + 16 + count;
if (num_left < (uint)i)
stop_decoding(JPGD_BAD_DHT_MARKER);
num_left -= i;
if ((index & 0x10) > 0x10)
stop_decoding(JPGD_BAD_DHT_INDEX);
index = (index & 0x0F) + ((index & 0x10) >> 4) * (JPGD_MAX_HUFF_TABLES >> 1);
if (index >= JPGD_MAX_HUFF_TABLES)
stop_decoding(JPGD_BAD_DHT_INDEX);
if (!m_huff_num[index])
m_huff_num[index] = (uint8*)alloc(17);
if (!m_huff_val[index])
m_huff_val[index] = (uint8*)alloc(256);
m_huff_ac[index] = (index & 0x10) != 0;
memcpy(m_huff_num[index], huff_num, 17);
memcpy(m_huff_val[index], huff_val, 256);
}
}
// Read a quantization table.
void jpeg_decoder::read_dqt_marker()
{
int n, i, prec;
uint num_left;
uint temp;
num_left = get_bits(16);
if (num_left < 2)
stop_decoding(JPGD_BAD_DQT_MARKER);
num_left -= 2;
while (num_left)
{
n = get_bits(8);
prec = n >> 4;
n &= 0x0F;
if (n >= JPGD_MAX_QUANT_TABLES)
stop_decoding(JPGD_BAD_DQT_TABLE);
if (!m_quant[n])
m_quant[n] = (jpgd_quant_t*)alloc(64 * sizeof(jpgd_quant_t));
// read quantization entries, in zag order
for (i = 0; i < 64; i++)
{
temp = get_bits(8);
if (prec)
temp = (temp << 8) + get_bits(8);
m_quant[n][i] = static_cast<jpgd_quant_t>(temp);
}
i = 64 + 1;
if (prec)
i += 64;
if (num_left < (uint)i)
stop_decoding(JPGD_BAD_DQT_LENGTH);
num_left -= i;
}
}
// Read the start of frame (SOF) marker.
void jpeg_decoder::read_sof_marker()
{
int i;
uint num_left;
num_left = get_bits(16);
/* precision: sorry, only 8-bit precision is supported */
if (get_bits(8) != 8)
stop_decoding(JPGD_BAD_PRECISION);
m_image_y_size = get_bits(16);
if ((m_image_y_size < 1) || (m_image_y_size > JPGD_MAX_HEIGHT))
stop_decoding(JPGD_BAD_HEIGHT);
m_image_x_size = get_bits(16);
if ((m_image_x_size < 1) || (m_image_x_size > JPGD_MAX_WIDTH))
stop_decoding(JPGD_BAD_WIDTH);
m_comps_in_frame = get_bits(8);
if (m_comps_in_frame > JPGD_MAX_COMPONENTS)
stop_decoding(JPGD_TOO_MANY_COMPONENTS);
if (num_left != (uint)(m_comps_in_frame * 3 + 8))
stop_decoding(JPGD_BAD_SOF_LENGTH);
for (i = 0; i < m_comps_in_frame; i++)
{
m_comp_ident[i] = get_bits(8);
m_comp_h_samp[i] = get_bits(4);
m_comp_v_samp[i] = get_bits(4);
if (!m_comp_h_samp[i] || !m_comp_v_samp[i] || (m_comp_h_samp[i] > 2) || (m_comp_v_samp[i] > 2))
stop_decoding(JPGD_UNSUPPORTED_SAMP_FACTORS);
m_comp_quant[i] = get_bits(8);
if (m_comp_quant[i] >= JPGD_MAX_QUANT_TABLES)
stop_decoding(JPGD_DECODE_ERROR);
}
}
// Used to skip unrecognized markers.
void jpeg_decoder::skip_variable_marker()
{
uint num_left;
num_left = get_bits(16);
if (num_left < 2)
stop_decoding(JPGD_BAD_VARIABLE_MARKER);
num_left -= 2;
while (num_left)
{
get_bits(8);
num_left--;
}
}
// Read a define restart interval (DRI) marker.
void jpeg_decoder::read_dri_marker()
{
if (get_bits(16) != 4)
stop_decoding(JPGD_BAD_DRI_LENGTH);
m_restart_interval = get_bits(16);
}
// Read a start of scan (SOS) marker.
void jpeg_decoder::read_sos_marker()
{
uint num_left;
int i, ci, n, c, cc;
num_left = get_bits(16);
n = get_bits(8);
m_comps_in_scan = n;
num_left -= 3;
if ((num_left != (uint)(n * 2 + 3)) || (n < 1) || (n > JPGD_MAX_COMPS_IN_SCAN))
stop_decoding(JPGD_BAD_SOS_LENGTH);
for (i = 0; i < n; i++)
{
cc = get_bits(8);
c = get_bits(8);
num_left -= 2;
for (ci = 0; ci < m_comps_in_frame; ci++)
if (cc == m_comp_ident[ci])
break;
if (ci >= m_comps_in_frame)
stop_decoding(JPGD_BAD_SOS_COMP_ID);
if (ci >= JPGD_MAX_COMPONENTS)
stop_decoding(JPGD_DECODE_ERROR);
m_comp_list[i] = ci;
m_comp_dc_tab[ci] = (c >> 4) & 15;
m_comp_ac_tab[ci] = (c & 15) + (JPGD_MAX_HUFF_TABLES >> 1);
if (m_comp_dc_tab[ci] >= JPGD_MAX_HUFF_TABLES)
stop_decoding(JPGD_DECODE_ERROR);
if (m_comp_ac_tab[ci] >= JPGD_MAX_HUFF_TABLES)
stop_decoding(JPGD_DECODE_ERROR);
}
m_spectral_start = get_bits(8);
m_spectral_end = get_bits(8);
m_successive_high = get_bits(4);
m_successive_low = get_bits(4);
if (!m_progressive_flag)
{
m_spectral_start = 0;
m_spectral_end = 63;
}
num_left -= 3;
/* read past whatever is num_left */
while (num_left)
{
get_bits(8);
num_left--;
}
}
// Finds the next marker.
int jpeg_decoder::next_marker()
{
uint c, bytes;
bytes = 0;
do
{
do
{
bytes++;
c = get_bits(8);
} while (c != 0xFF);
do
{
c = get_bits(8);
} while (c == 0xFF);
} while (c == 0);
// If bytes > 0 here, there where extra bytes before the marker (not good).
return c;
}
// Process markers. Returns when an SOFx, SOI, EOI, or SOS marker is
// encountered.
int jpeg_decoder::process_markers()
{
int c;
for (; ; )
{
c = next_marker();
switch (c)
{
case M_SOF0:
case M_SOF1:
case M_SOF2:
case M_SOF3:
case M_SOF5:
case M_SOF6:
case M_SOF7:
// case M_JPG:
case M_SOF9:
case M_SOF10:
case M_SOF11:
case M_SOF13:
case M_SOF14:
case M_SOF15:
case M_SOI:
case M_EOI:
case M_SOS:
{
return c;
}
case M_DHT:
{
read_dht_marker();
break;
}
// No arithmitic support - dumb patents!
case M_DAC:
{
stop_decoding(JPGD_NO_ARITHMITIC_SUPPORT);
break;
}
case M_DQT:
{
read_dqt_marker();
break;
}
case M_DRI:
{
read_dri_marker();
break;
}
//case M_APP0: /* no need to read the JFIF marker */
case M_JPG:
case M_RST0: /* no parameters */
case M_RST1:
case M_RST2:
case M_RST3:
case M_RST4:
case M_RST5:
case M_RST6:
case M_RST7:
case M_TEM:
{
stop_decoding(JPGD_UNEXPECTED_MARKER);
break;
}
default: /* must be DNL, DHP, EXP, APPn, JPGn, COM, or RESn or APP0 */
{
skip_variable_marker();
break;
}
}
}
}
// Finds the start of image (SOI) marker.
void jpeg_decoder::locate_soi_marker()
{
uint lastchar, thischar;
uint bytesleft;
lastchar = get_bits(8);
thischar = get_bits(8);
/* ok if it's a normal JPEG file without a special header */
if ((lastchar == 0xFF) && (thischar == M_SOI))
return;
bytesleft = 4096;
for (; ; )
{
if (--bytesleft == 0)
stop_decoding(JPGD_NOT_JPEG);
lastchar = thischar;
thischar = get_bits(8);
if (lastchar == 0xFF)
{
if (thischar == M_SOI)
break;
else if (thischar == M_EOI) // get_bits will keep returning M_EOI if we read past the end
stop_decoding(JPGD_NOT_JPEG);
}
}
// Check the next character after marker: if it's not 0xFF, it can't be the start of the next marker, so the file is bad.
thischar = (m_bit_buf >> 24) & 0xFF;
if (thischar != 0xFF)
stop_decoding(JPGD_NOT_JPEG);
}
// Find a start of frame (SOF) marker.
void jpeg_decoder::locate_sof_marker()
{
locate_soi_marker();
int c = process_markers();
switch (c)
{
case M_SOF2:
{
m_progressive_flag = JPGD_TRUE;
read_sof_marker();
break;
}
case M_SOF0: /* baseline DCT */
case M_SOF1: /* extended sequential DCT */
{
read_sof_marker();
break;
}
case M_SOF9: /* Arithmitic coding */
{
stop_decoding(JPGD_NO_ARITHMITIC_SUPPORT);
break;
}
default:
{
stop_decoding(JPGD_UNSUPPORTED_MARKER);
break;
}
}
}
// Find a start of scan (SOS) marker.
int jpeg_decoder::locate_sos_marker()
{
int c;
c = process_markers();
if (c == M_EOI)
return JPGD_FALSE;
else if (c != M_SOS)
stop_decoding(JPGD_UNEXPECTED_MARKER);
read_sos_marker();
return JPGD_TRUE;
}
// Reset everything to default/uninitialized state.
void jpeg_decoder::init(jpeg_decoder_stream* pStream, uint32_t flags)
{
m_flags = flags;
m_pMem_blocks = nullptr;
m_error_code = JPGD_SUCCESS;
m_ready_flag = false;
m_image_x_size = m_image_y_size = 0;
m_pStream = pStream;
m_progressive_flag = JPGD_FALSE;
memset(m_huff_ac, 0, sizeof(m_huff_ac));
memset(m_huff_num, 0, sizeof(m_huff_num));
memset(m_huff_val, 0, sizeof(m_huff_val));
memset(m_quant, 0, sizeof(m_quant));
m_scan_type = 0;
m_comps_in_frame = 0;
memset(m_comp_h_samp, 0, sizeof(m_comp_h_samp));
memset(m_comp_v_samp, 0, sizeof(m_comp_v_samp));
memset(m_comp_quant, 0, sizeof(m_comp_quant));
memset(m_comp_ident, 0, sizeof(m_comp_ident));
memset(m_comp_h_blocks, 0, sizeof(m_comp_h_blocks));
memset(m_comp_v_blocks, 0, sizeof(m_comp_v_blocks));
m_comps_in_scan = 0;
memset(m_comp_list, 0, sizeof(m_comp_list));
memset(m_comp_dc_tab, 0, sizeof(m_comp_dc_tab));
memset(m_comp_ac_tab, 0, sizeof(m_comp_ac_tab));
m_spectral_start = 0;
m_spectral_end = 0;
m_successive_low = 0;
m_successive_high = 0;
m_max_mcu_x_size = 0;
m_max_mcu_y_size = 0;
m_blocks_per_mcu = 0;
m_max_blocks_per_row = 0;
m_mcus_per_row = 0;
m_mcus_per_col = 0;
memset(m_mcu_org, 0, sizeof(m_mcu_org));
m_total_lines_left = 0;
m_mcu_lines_left = 0;
m_num_buffered_scanlines = 0;
m_real_dest_bytes_per_scan_line = 0;
m_dest_bytes_per_scan_line = 0;
m_dest_bytes_per_pixel = 0;
memset(m_pHuff_tabs, 0, sizeof(m_pHuff_tabs));
memset(m_dc_coeffs, 0, sizeof(m_dc_coeffs));
memset(m_ac_coeffs, 0, sizeof(m_ac_coeffs));
memset(m_block_y_mcu, 0, sizeof(m_block_y_mcu));
m_eob_run = 0;
m_pIn_buf_ofs = m_in_buf;
m_in_buf_left = 0;
m_eof_flag = false;
m_tem_flag = 0;
memset(m_in_buf_pad_start, 0, sizeof(m_in_buf_pad_start));
memset(m_in_buf, 0, sizeof(m_in_buf));
memset(m_in_buf_pad_end, 0, sizeof(m_in_buf_pad_end));
m_restart_interval = 0;
m_restarts_left = 0;
m_next_restart_num = 0;
m_max_mcus_per_row = 0;
m_max_blocks_per_mcu = 0;
m_max_mcus_per_col = 0;
memset(m_last_dc_val, 0, sizeof(m_last_dc_val));
m_pMCU_coefficients = nullptr;
m_pSample_buf = nullptr;
m_pSample_buf_prev = nullptr;
m_sample_buf_prev_valid = false;
m_total_bytes_read = 0;
m_pScan_line_0 = nullptr;
m_pScan_line_1 = nullptr;
// Ready the input buffer.
prep_in_buffer();
// Prime the bit buffer.
m_bits_left = 16;
m_bit_buf = 0;
get_bits(16);
get_bits(16);
for (int i = 0; i < JPGD_MAX_BLOCKS_PER_MCU; i++)
m_mcu_block_max_zag[i] = 64;
}
#define SCALEBITS 16
#define ONE_HALF ((int) 1 << (SCALEBITS-1))
#define FIX(x) ((int) ((x) * (1L<<SCALEBITS) + 0.5f))
// Create a few tables that allow us to quickly convert YCbCr to RGB.
void jpeg_decoder::create_look_ups()
{
for (int i = 0; i <= 255; i++)
{
int k = i - 128;
m_crr[i] = (FIX(1.40200f) * k + ONE_HALF) >> SCALEBITS;
m_cbb[i] = (FIX(1.77200f) * k + ONE_HALF) >> SCALEBITS;
m_crg[i] = (-FIX(0.71414f)) * k;
m_cbg[i] = (-FIX(0.34414f)) * k + ONE_HALF;
}
}
// This method throws back into the stream any bytes that where read
// into the bit buffer during initial marker scanning.
void jpeg_decoder::fix_in_buffer()
{
// In case any 0xFF's where pulled into the buffer during marker scanning.
assert((m_bits_left & 7) == 0);
if (m_bits_left == 16)
stuff_char((uint8)(m_bit_buf & 0xFF));
if (m_bits_left >= 8)
stuff_char((uint8)((m_bit_buf >> 8) & 0xFF));
stuff_char((uint8)((m_bit_buf >> 16) & 0xFF));
stuff_char((uint8)((m_bit_buf >> 24) & 0xFF));
m_bits_left = 16;
get_bits_no_markers(16);
get_bits_no_markers(16);
}
void jpeg_decoder::transform_mcu(int mcu_row)
{
jpgd_block_t* pSrc_ptr = m_pMCU_coefficients;
if (mcu_row * m_blocks_per_mcu >= m_max_blocks_per_row)
stop_decoding(JPGD_DECODE_ERROR);
uint8* pDst_ptr = m_pSample_buf + mcu_row * m_blocks_per_mcu * 64;
for (int mcu_block = 0; mcu_block < m_blocks_per_mcu; mcu_block++)
{
idct(pSrc_ptr, pDst_ptr, m_mcu_block_max_zag[mcu_block]);
pSrc_ptr += 64;
pDst_ptr += 64;
}
}
// Loads and dequantizes the next row of (already decoded) coefficients.
// Progressive images only.
void jpeg_decoder::load_next_row()
{
int i;
jpgd_block_t* p;
jpgd_quant_t* q;
int mcu_row, mcu_block, row_block = 0;
int component_num, component_id;
int block_x_mcu[JPGD_MAX_COMPONENTS];
memset(block_x_mcu, 0, JPGD_MAX_COMPONENTS * sizeof(int));
for (mcu_row = 0; mcu_row < m_mcus_per_row; mcu_row++)
{
int block_x_mcu_ofs = 0, block_y_mcu_ofs = 0;
for (mcu_block = 0; mcu_block < m_blocks_per_mcu; mcu_block++)
{
component_id = m_mcu_org[mcu_block];
if (m_comp_quant[component_id] >= JPGD_MAX_QUANT_TABLES)
stop_decoding(JPGD_DECODE_ERROR);
q = m_quant[m_comp_quant[component_id]];
p = m_pMCU_coefficients + 64 * mcu_block;
jpgd_block_t* pAC = coeff_buf_getp(m_ac_coeffs[component_id], block_x_mcu[component_id] + block_x_mcu_ofs, m_block_y_mcu[component_id] + block_y_mcu_ofs);
jpgd_block_t* pDC = coeff_buf_getp(m_dc_coeffs[component_id], block_x_mcu[component_id] + block_x_mcu_ofs, m_block_y_mcu[component_id] + block_y_mcu_ofs);
p[0] = pDC[0];
memcpy(&p[1], &pAC[1], 63 * sizeof(jpgd_block_t));
for (i = 63; i > 0; i--)
if (p[g_ZAG[i]])
break;
m_mcu_block_max_zag[mcu_block] = i + 1;
for (; i >= 0; i--)
if (p[g_ZAG[i]])
p[g_ZAG[i]] = static_cast<jpgd_block_t>(p[g_ZAG[i]] * q[i]);
row_block++;
if (m_comps_in_scan == 1)
block_x_mcu[component_id]++;
else
{
if (++block_x_mcu_ofs == m_comp_h_samp[component_id])
{
block_x_mcu_ofs = 0;
if (++block_y_mcu_ofs == m_comp_v_samp[component_id])
{
block_y_mcu_ofs = 0;
block_x_mcu[component_id] += m_comp_h_samp[component_id];
}
}
}
}
transform_mcu(mcu_row);
}
if (m_comps_in_scan == 1)
m_block_y_mcu[m_comp_list[0]]++;
else
{
for (component_num = 0; component_num < m_comps_in_scan; component_num++)
{
component_id = m_comp_list[component_num];
m_block_y_mcu[component_id] += m_comp_v_samp[component_id];
}
}
}
// Restart interval processing.
void jpeg_decoder::process_restart()
{
int i;
int c = 0;
// Align to a byte boundry
// FIXME: Is this really necessary? get_bits_no_markers() never reads in markers!
//get_bits_no_markers(m_bits_left & 7);
// Let's scan a little bit to find the marker, but not _too_ far.
// 1536 is a "fudge factor" that determines how much to scan.
for (i = 1536; i > 0; i--)
if (get_char() == 0xFF)
break;
if (i == 0)
stop_decoding(JPGD_BAD_RESTART_MARKER);
for (; i > 0; i--)
if ((c = get_char()) != 0xFF)
break;
if (i == 0)
stop_decoding(JPGD_BAD_RESTART_MARKER);
// Is it the expected marker? If not, something bad happened.
if (c != (m_next_restart_num + M_RST0))
stop_decoding(JPGD_BAD_RESTART_MARKER);
// Reset each component's DC prediction values.
memset(&m_last_dc_val, 0, m_comps_in_frame * sizeof(uint));
m_eob_run = 0;
m_restarts_left = m_restart_interval;
m_next_restart_num = (m_next_restart_num + 1) & 7;
// Get the bit buffer going again...
m_bits_left = 16;
get_bits_no_markers(16);
get_bits_no_markers(16);
}
static inline int dequantize_ac(int c, int q) { c *= q; return c; }
// Decodes and dequantizes the next row of coefficients.
void jpeg_decoder::decode_next_row()
{
int row_block = 0;
for (int mcu_row = 0; mcu_row < m_mcus_per_row; mcu_row++)
{
if ((m_restart_interval) && (m_restarts_left == 0))
process_restart();
jpgd_block_t* p = m_pMCU_coefficients;
for (int mcu_block = 0; mcu_block < m_blocks_per_mcu; mcu_block++, p += 64)
{
int component_id = m_mcu_org[mcu_block];
if (m_comp_quant[component_id] >= JPGD_MAX_QUANT_TABLES)
stop_decoding(JPGD_DECODE_ERROR);
jpgd_quant_t* q = m_quant[m_comp_quant[component_id]];
int r, s;
s = huff_decode(m_pHuff_tabs[m_comp_dc_tab[component_id]], r);
if (s >= 16)
stop_decoding(JPGD_DECODE_ERROR);
s = JPGD_HUFF_EXTEND(r, s);
m_last_dc_val[component_id] = (s += m_last_dc_val[component_id]);
p[0] = static_cast<jpgd_block_t>(s * q[0]);
int prev_num_set = m_mcu_block_max_zag[mcu_block];
huff_tables* pH = m_pHuff_tabs[m_comp_ac_tab[component_id]];
int k;
for (k = 1; k < 64; k++)
{
int extra_bits;
s = huff_decode(pH, extra_bits);
r = s >> 4;
s &= 15;
if (s)
{
if (r)
{
if ((k + r) > 63)
stop_decoding(JPGD_DECODE_ERROR);
if (k < prev_num_set)
{
int n = JPGD_MIN(r, prev_num_set - k);
int kt = k;
while (n--)
p[g_ZAG[kt++]] = 0;
}
k += r;
}
s = JPGD_HUFF_EXTEND(extra_bits, s);
if (k >= 64)
stop_decoding(JPGD_DECODE_ERROR);
p[g_ZAG[k]] = static_cast<jpgd_block_t>(dequantize_ac(s, q[k])); //s * q[k];
}
else
{
if (r == 15)
{
if ((k + 16) > 64)
stop_decoding(JPGD_DECODE_ERROR);
if (k < prev_num_set)
{
int n = JPGD_MIN(16, prev_num_set - k);
int kt = k;
while (n--)
{
if (kt > 63)
stop_decoding(JPGD_DECODE_ERROR);
p[g_ZAG[kt++]] = 0;
}
}
k += 16 - 1; // - 1 because the loop counter is k
if (p[g_ZAG[k & 63]] != 0)
stop_decoding(JPGD_DECODE_ERROR);
}
else
break;
}
}
if (k < prev_num_set)
{
int kt = k;
while (kt < prev_num_set)
p[g_ZAG[kt++]] = 0;
}
m_mcu_block_max_zag[mcu_block] = k;
row_block++;
}
transform_mcu(mcu_row);
m_restarts_left--;
}
}
// YCbCr H1V1 (1x1:1:1, 3 m_blocks per MCU) to RGB
void jpeg_decoder::H1V1Convert()
{
int row = m_max_mcu_y_size - m_mcu_lines_left;
uint8* d = m_pScan_line_0;
uint8* s = m_pSample_buf + row * 8;
for (int i = m_max_mcus_per_row; i > 0; i--)
{
for (int j = 0; j < 8; j++)
{
int y = s[j];
int cb = s[64 + j];
int cr = s[128 + j];
d[0] = clamp(y + m_crr[cr]);
d[1] = clamp(y + ((m_crg[cr] + m_cbg[cb]) >> 16));
d[2] = clamp(y + m_cbb[cb]);
d[3] = 255;
d += 4;
}
s += 64 * 3;
}
}
// YCbCr H2V1 (2x1:1:1, 4 m_blocks per MCU) to RGB
void jpeg_decoder::H2V1Convert()
{
int row = m_max_mcu_y_size - m_mcu_lines_left;
uint8* d0 = m_pScan_line_0;
uint8* y = m_pSample_buf + row * 8;
uint8* c = m_pSample_buf + 2 * 64 + row * 8;
for (int i = m_max_mcus_per_row; i > 0; i--)
{
for (int l = 0; l < 2; l++)
{
for (int j = 0; j < 4; j++)
{
int cb = c[0];
int cr = c[64];
int rc = m_crr[cr];
int gc = ((m_crg[cr] + m_cbg[cb]) >> 16);
int bc = m_cbb[cb];
int yy = y[j << 1];
d0[0] = clamp(yy + rc);
d0[1] = clamp(yy + gc);
d0[2] = clamp(yy + bc);
d0[3] = 255;
yy = y[(j << 1) + 1];
d0[4] = clamp(yy + rc);
d0[5] = clamp(yy + gc);
d0[6] = clamp(yy + bc);
d0[7] = 255;
d0 += 8;
c++;
}
y += 64;
}
y += 64 * 4 - 64 * 2;
c += 64 * 4 - 8;
}
}
// YCbCr H2V1 (2x1:1:1, 4 m_blocks per MCU) to RGB
void jpeg_decoder::H2V1ConvertFiltered()
{
const uint BLOCKS_PER_MCU = 4;
int row = m_max_mcu_y_size - m_mcu_lines_left;
uint8* d0 = m_pScan_line_0;
const int half_image_x_size = (m_image_x_size >> 1) - 1;
const int row_x8 = row * 8;
for (int x = 0; x < m_image_x_size; x++)
{
int y = m_pSample_buf[check_sample_buf_ofs((x >> 4) * BLOCKS_PER_MCU * 64 + ((x & 8) ? 64 : 0) + (x & 7) + row_x8)];
int c_x0 = (x - 1) >> 1;
int c_x1 = JPGD_MIN(c_x0 + 1, half_image_x_size);
c_x0 = JPGD_MAX(c_x0, 0);
int a = (c_x0 >> 3) * BLOCKS_PER_MCU * 64 + (c_x0 & 7) + row_x8 + 128;
int cb0 = m_pSample_buf[check_sample_buf_ofs(a)];
int cr0 = m_pSample_buf[check_sample_buf_ofs(a + 64)];
int b = (c_x1 >> 3) * BLOCKS_PER_MCU * 64 + (c_x1 & 7) + row_x8 + 128;
int cb1 = m_pSample_buf[check_sample_buf_ofs(b)];
int cr1 = m_pSample_buf[check_sample_buf_ofs(b + 64)];
int w0 = (x & 1) ? 3 : 1;
int w1 = (x & 1) ? 1 : 3;
int cb = (cb0 * w0 + cb1 * w1 + 2) >> 2;
int cr = (cr0 * w0 + cr1 * w1 + 2) >> 2;
int rc = m_crr[cr];
int gc = ((m_crg[cr] + m_cbg[cb]) >> 16);
int bc = m_cbb[cb];
d0[0] = clamp(y + rc);
d0[1] = clamp(y + gc);
d0[2] = clamp(y + bc);
d0[3] = 255;
d0 += 4;
}
}
// YCbCr H2V1 (1x2:1:1, 4 m_blocks per MCU) to RGB
void jpeg_decoder::H1V2Convert()
{
int row = m_max_mcu_y_size - m_mcu_lines_left;
uint8* d0 = m_pScan_line_0;
uint8* d1 = m_pScan_line_1;
uint8* y;
uint8* c;
if (row < 8)
y = m_pSample_buf + row * 8;
else
y = m_pSample_buf + 64 * 1 + (row & 7) * 8;
c = m_pSample_buf + 64 * 2 + (row >> 1) * 8;
for (int i = m_max_mcus_per_row; i > 0; i--)
{
for (int j = 0; j < 8; j++)
{
int cb = c[0 + j];
int cr = c[64 + j];
int rc = m_crr[cr];
int gc = ((m_crg[cr] + m_cbg[cb]) >> 16);
int bc = m_cbb[cb];
int yy = y[j];
d0[0] = clamp(yy + rc);
d0[1] = clamp(yy + gc);
d0[2] = clamp(yy + bc);
d0[3] = 255;
yy = y[8 + j];
d1[0] = clamp(yy + rc);
d1[1] = clamp(yy + gc);
d1[2] = clamp(yy + bc);
d1[3] = 255;
d0 += 4;
d1 += 4;
}
y += 64 * 4;
c += 64 * 4;
}
}
// YCbCr H2V1 (1x2:1:1, 4 m_blocks per MCU) to RGB
void jpeg_decoder::H1V2ConvertFiltered()
{
const uint BLOCKS_PER_MCU = 4;
int y = m_image_y_size - m_total_lines_left;
int row = y & 15;
const int half_image_y_size = (m_image_y_size >> 1) - 1;
uint8* d0 = m_pScan_line_0;
const int w0 = (row & 1) ? 3 : 1;
const int w1 = (row & 1) ? 1 : 3;
int c_y0 = (y - 1) >> 1;
int c_y1 = JPGD_MIN(c_y0 + 1, half_image_y_size);
const uint8_t* p_YSamples = m_pSample_buf;
const uint8_t* p_C0Samples = m_pSample_buf;
if ((c_y0 >= 0) && (((row & 15) == 0) || ((row & 15) == 15)) && (m_total_lines_left > 1))
{
assert(y > 0);
assert(m_sample_buf_prev_valid);
if ((row & 15) == 15)
p_YSamples = m_pSample_buf_prev;
p_C0Samples = m_pSample_buf_prev;
}
const int y_sample_base_ofs = ((row & 8) ? 64 : 0) + (row & 7) * 8;
const int y0_base = (c_y0 & 7) * 8 + 128;
const int y1_base = (c_y1 & 7) * 8 + 128;
for (int x = 0; x < m_image_x_size; x++)
{
const int base_ofs = (x >> 3) * BLOCKS_PER_MCU * 64 + (x & 7);
int y_sample = p_YSamples[check_sample_buf_ofs(base_ofs + y_sample_base_ofs)];
int a = base_ofs + y0_base;
int cb0_sample = p_C0Samples[check_sample_buf_ofs(a)];
int cr0_sample = p_C0Samples[check_sample_buf_ofs(a + 64)];
int b = base_ofs + y1_base;
int cb1_sample = m_pSample_buf[check_sample_buf_ofs(b)];
int cr1_sample = m_pSample_buf[check_sample_buf_ofs(b + 64)];
int cb = (cb0_sample * w0 + cb1_sample * w1 + 2) >> 2;
int cr = (cr0_sample * w0 + cr1_sample * w1 + 2) >> 2;
int rc = m_crr[cr];
int gc = ((m_crg[cr] + m_cbg[cb]) >> 16);
int bc = m_cbb[cb];
d0[0] = clamp(y_sample + rc);
d0[1] = clamp(y_sample + gc);
d0[2] = clamp(y_sample + bc);
d0[3] = 255;
d0 += 4;
}
}
// YCbCr H2V2 (2x2:1:1, 6 m_blocks per MCU) to RGB
void jpeg_decoder::H2V2Convert()
{
int row = m_max_mcu_y_size - m_mcu_lines_left;
uint8* d0 = m_pScan_line_0;
uint8* d1 = m_pScan_line_1;
uint8* y;
uint8* c;
if (row < 8)
y = m_pSample_buf + row * 8;
else
y = m_pSample_buf + 64 * 2 + (row & 7) * 8;
c = m_pSample_buf + 64 * 4 + (row >> 1) * 8;
for (int i = m_max_mcus_per_row; i > 0; i--)
{
for (int l = 0; l < 2; l++)
{
for (int j = 0; j < 8; j += 2)
{
int cb = c[0];
int cr = c[64];
int rc = m_crr[cr];
int gc = ((m_crg[cr] + m_cbg[cb]) >> 16);
int bc = m_cbb[cb];
int yy = y[j];
d0[0] = clamp(yy + rc);
d0[1] = clamp(yy + gc);
d0[2] = clamp(yy + bc);
d0[3] = 255;
yy = y[j + 1];
d0[4] = clamp(yy + rc);
d0[5] = clamp(yy + gc);
d0[6] = clamp(yy + bc);
d0[7] = 255;
yy = y[j + 8];
d1[0] = clamp(yy + rc);
d1[1] = clamp(yy + gc);
d1[2] = clamp(yy + bc);
d1[3] = 255;
yy = y[j + 8 + 1];
d1[4] = clamp(yy + rc);
d1[5] = clamp(yy + gc);
d1[6] = clamp(yy + bc);
d1[7] = 255;
d0 += 8;
d1 += 8;
c++;
}
y += 64;
}
y += 64 * 6 - 64 * 2;
c += 64 * 6 - 8;
}
}
uint32_t jpeg_decoder::H2V2ConvertFiltered()
{
const uint BLOCKS_PER_MCU = 6;
int y = m_image_y_size - m_total_lines_left;
int row = y & 15;
const int half_image_y_size = (m_image_y_size >> 1) - 1;
uint8* d0 = m_pScan_line_0;
int c_y0 = (y - 1) >> 1;
int c_y1 = JPGD_MIN(c_y0 + 1, half_image_y_size);
const uint8_t* p_YSamples = m_pSample_buf;
const uint8_t* p_C0Samples = m_pSample_buf;
if ((c_y0 >= 0) && (((row & 15) == 0) || ((row & 15) == 15)) && (m_total_lines_left > 1))
{
assert(y > 0);
assert(m_sample_buf_prev_valid);
if ((row & 15) == 15)
p_YSamples = m_pSample_buf_prev;
p_C0Samples = m_pSample_buf_prev;
}
const int y_sample_base_ofs = ((row & 8) ? 128 : 0) + (row & 7) * 8;
const int y0_base = (c_y0 & 7) * 8 + 256;
const int y1_base = (c_y1 & 7) * 8 + 256;
const int half_image_x_size = (m_image_x_size >> 1) - 1;
static const uint8_t s_muls[2][2][4] =
{
{ { 1, 3, 3, 9 }, { 3, 9, 1, 3 }, },
{ { 3, 1, 9, 3 }, { 9, 3, 3, 1 } }
};
if (((row & 15) >= 1) && ((row & 15) <= 14))
{
assert((row & 1) == 1);
assert(((y + 1 - 1) >> 1) == c_y0);
assert(p_YSamples == m_pSample_buf);
assert(p_C0Samples == m_pSample_buf);
uint8* d1 = m_pScan_line_1;
const int y_sample_base_ofs1 = (((row + 1) & 8) ? 128 : 0) + ((row + 1) & 7) * 8;
for (int x = 0; x < m_image_x_size; x++)
{
int k = (x >> 4) * BLOCKS_PER_MCU * 64 + ((x & 8) ? 64 : 0) + (x & 7);
int y_sample0 = p_YSamples[check_sample_buf_ofs(k + y_sample_base_ofs)];
int y_sample1 = p_YSamples[check_sample_buf_ofs(k + y_sample_base_ofs1)];
int c_x0 = (x - 1) >> 1;
int c_x1 = JPGD_MIN(c_x0 + 1, half_image_x_size);
c_x0 = JPGD_MAX(c_x0, 0);
int a = (c_x0 >> 3) * BLOCKS_PER_MCU * 64 + (c_x0 & 7);
int cb00_sample = p_C0Samples[check_sample_buf_ofs(a + y0_base)];
int cr00_sample = p_C0Samples[check_sample_buf_ofs(a + y0_base + 64)];
int cb01_sample = m_pSample_buf[check_sample_buf_ofs(a + y1_base)];
int cr01_sample = m_pSample_buf[check_sample_buf_ofs(a + y1_base + 64)];
int b = (c_x1 >> 3) * BLOCKS_PER_MCU * 64 + (c_x1 & 7);
int cb10_sample = p_C0Samples[check_sample_buf_ofs(b + y0_base)];
int cr10_sample = p_C0Samples[check_sample_buf_ofs(b + y0_base + 64)];
int cb11_sample = m_pSample_buf[check_sample_buf_ofs(b + y1_base)];
int cr11_sample = m_pSample_buf[check_sample_buf_ofs(b + y1_base + 64)];
{
const uint8_t* pMuls = &s_muls[row & 1][x & 1][0];
int cb = (cb00_sample * pMuls[0] + cb01_sample * pMuls[1] + cb10_sample * pMuls[2] + cb11_sample * pMuls[3] + 8) >> 4;
int cr = (cr00_sample * pMuls[0] + cr01_sample * pMuls[1] + cr10_sample * pMuls[2] + cr11_sample * pMuls[3] + 8) >> 4;
int rc = m_crr[cr];
int gc = ((m_crg[cr] + m_cbg[cb]) >> 16);
int bc = m_cbb[cb];
d0[0] = clamp(y_sample0 + rc);
d0[1] = clamp(y_sample0 + gc);
d0[2] = clamp(y_sample0 + bc);
d0[3] = 255;
d0 += 4;
}
{
const uint8_t* pMuls = &s_muls[(row + 1) & 1][x & 1][0];
int cb = (cb00_sample * pMuls[0] + cb01_sample * pMuls[1] + cb10_sample * pMuls[2] + cb11_sample * pMuls[3] + 8) >> 4;
int cr = (cr00_sample * pMuls[0] + cr01_sample * pMuls[1] + cr10_sample * pMuls[2] + cr11_sample * pMuls[3] + 8) >> 4;
int rc = m_crr[cr];
int gc = ((m_crg[cr] + m_cbg[cb]) >> 16);
int bc = m_cbb[cb];
d1[0] = clamp(y_sample1 + rc);
d1[1] = clamp(y_sample1 + gc);
d1[2] = clamp(y_sample1 + bc);
d1[3] = 255;
d1 += 4;
}
if (((x & 1) == 1) && (x < m_image_x_size - 1))
{
const int nx = x + 1;
assert(c_x0 == (nx - 1) >> 1);
k = (nx >> 4) * BLOCKS_PER_MCU * 64 + ((nx & 8) ? 64 : 0) + (nx & 7);
y_sample0 = p_YSamples[check_sample_buf_ofs(k + y_sample_base_ofs)];
y_sample1 = p_YSamples[check_sample_buf_ofs(k + y_sample_base_ofs1)];
{
const uint8_t* pMuls = &s_muls[row & 1][nx & 1][0];
int cb = (cb00_sample * pMuls[0] + cb01_sample * pMuls[1] + cb10_sample * pMuls[2] + cb11_sample * pMuls[3] + 8) >> 4;
int cr = (cr00_sample * pMuls[0] + cr01_sample * pMuls[1] + cr10_sample * pMuls[2] + cr11_sample * pMuls[3] + 8) >> 4;
int rc = m_crr[cr];
int gc = ((m_crg[cr] + m_cbg[cb]) >> 16);
int bc = m_cbb[cb];
d0[0] = clamp(y_sample0 + rc);
d0[1] = clamp(y_sample0 + gc);
d0[2] = clamp(y_sample0 + bc);
d0[3] = 255;
d0 += 4;
}
{
const uint8_t* pMuls = &s_muls[(row + 1) & 1][nx & 1][0];
int cb = (cb00_sample * pMuls[0] + cb01_sample * pMuls[1] + cb10_sample * pMuls[2] + cb11_sample * pMuls[3] + 8) >> 4;
int cr = (cr00_sample * pMuls[0] + cr01_sample * pMuls[1] + cr10_sample * pMuls[2] + cr11_sample * pMuls[3] + 8) >> 4;
int rc = m_crr[cr];
int gc = ((m_crg[cr] + m_cbg[cb]) >> 16);
int bc = m_cbb[cb];
d1[0] = clamp(y_sample1 + rc);
d1[1] = clamp(y_sample1 + gc);
d1[2] = clamp(y_sample1 + bc);
d1[3] = 255;
d1 += 4;
}
++x;
}
}
return 2;
}
else
{
for (int x = 0; x < m_image_x_size; x++)
{
int y_sample = p_YSamples[check_sample_buf_ofs((x >> 4) * BLOCKS_PER_MCU * 64 + ((x & 8) ? 64 : 0) + (x & 7) + y_sample_base_ofs)];
int c_x0 = (x - 1) >> 1;
int c_x1 = JPGD_MIN(c_x0 + 1, half_image_x_size);
c_x0 = JPGD_MAX(c_x0, 0);
int a = (c_x0 >> 3) * BLOCKS_PER_MCU * 64 + (c_x0 & 7);
int cb00_sample = p_C0Samples[check_sample_buf_ofs(a + y0_base)];
int cr00_sample = p_C0Samples[check_sample_buf_ofs(a + y0_base + 64)];
int cb01_sample = m_pSample_buf[check_sample_buf_ofs(a + y1_base)];
int cr01_sample = m_pSample_buf[check_sample_buf_ofs(a + y1_base + 64)];
int b = (c_x1 >> 3) * BLOCKS_PER_MCU * 64 + (c_x1 & 7);
int cb10_sample = p_C0Samples[check_sample_buf_ofs(b + y0_base)];
int cr10_sample = p_C0Samples[check_sample_buf_ofs(b + y0_base + 64)];
int cb11_sample = m_pSample_buf[check_sample_buf_ofs(b + y1_base)];
int cr11_sample = m_pSample_buf[check_sample_buf_ofs(b + y1_base + 64)];
const uint8_t* pMuls = &s_muls[row & 1][x & 1][0];
int cb = (cb00_sample * pMuls[0] + cb01_sample * pMuls[1] + cb10_sample * pMuls[2] + cb11_sample * pMuls[3] + 8) >> 4;
int cr = (cr00_sample * pMuls[0] + cr01_sample * pMuls[1] + cr10_sample * pMuls[2] + cr11_sample * pMuls[3] + 8) >> 4;
int rc = m_crr[cr];
int gc = ((m_crg[cr] + m_cbg[cb]) >> 16);
int bc = m_cbb[cb];
d0[0] = clamp(y_sample + rc);
d0[1] = clamp(y_sample + gc);
d0[2] = clamp(y_sample + bc);
d0[3] = 255;
d0 += 4;
}
return 1;
}
}
// Y (1 block per MCU) to 8-bit grayscale
void jpeg_decoder::gray_convert()
{
int row = m_max_mcu_y_size - m_mcu_lines_left;
uint8* d = m_pScan_line_0;
uint8* s = m_pSample_buf + row * 8;
for (int i = m_max_mcus_per_row; i > 0; i--)
{
*(uint*)d = *(uint*)s;
*(uint*)(&d[4]) = *(uint*)(&s[4]);
s += 64;
d += 8;
}
}
// Find end of image (EOI) marker, so we can return to the user the exact size of the input stream.
void jpeg_decoder::find_eoi()
{
if (!m_progressive_flag)
{
// Attempt to read the EOI marker.
//get_bits_no_markers(m_bits_left & 7);
// Prime the bit buffer
m_bits_left = 16;
get_bits(16);
get_bits(16);
// The next marker _should_ be EOI
process_markers();
}
m_total_bytes_read -= m_in_buf_left;
}
int jpeg_decoder::decode_next_mcu_row()
{
if (setjmp(m_jmp_state))
return JPGD_FAILED;
const bool chroma_y_filtering = (m_flags & cFlagLinearChromaFiltering) && ((m_scan_type == JPGD_YH2V2) || (m_scan_type == JPGD_YH1V2));
if (chroma_y_filtering)
{
std::swap(m_pSample_buf, m_pSample_buf_prev);
m_sample_buf_prev_valid = true;
}
if (m_progressive_flag)
load_next_row();
else
decode_next_row();
// Find the EOI marker if that was the last row.
if (m_total_lines_left <= m_max_mcu_y_size)
find_eoi();
m_mcu_lines_left = m_max_mcu_y_size;
return 0;
}
int jpeg_decoder::decode(const void** pScan_line, uint* pScan_line_len)
{
if ((m_error_code) || (!m_ready_flag))
return JPGD_FAILED;
if (m_total_lines_left == 0)
return JPGD_DONE;
const bool chroma_y_filtering = (m_flags & cFlagLinearChromaFiltering) && ((m_scan_type == JPGD_YH2V2) || (m_scan_type == JPGD_YH1V2));
bool get_another_mcu_row = false;
bool got_mcu_early = false;
if (chroma_y_filtering)
{
if (m_total_lines_left == m_image_y_size)
get_another_mcu_row = true;
else if ((m_mcu_lines_left == 1) && (m_total_lines_left > 1))
{
get_another_mcu_row = true;
got_mcu_early = true;
}
}
else
{
get_another_mcu_row = (m_mcu_lines_left == 0);
}
if (get_another_mcu_row)
{
int status = decode_next_mcu_row();
if (status != 0)
return status;
}
switch (m_scan_type)
{
case JPGD_YH2V2:
{
if (m_flags & cFlagLinearChromaFiltering)
{
if (m_num_buffered_scanlines == 1)
{
*pScan_line = m_pScan_line_1;
}
else if (m_num_buffered_scanlines == 0)
{
m_num_buffered_scanlines = H2V2ConvertFiltered();
*pScan_line = m_pScan_line_0;
}
m_num_buffered_scanlines--;
}
else
{
if ((m_mcu_lines_left & 1) == 0)
{
H2V2Convert();
*pScan_line = m_pScan_line_0;
}
else
*pScan_line = m_pScan_line_1;
}
break;
}
case JPGD_YH2V1:
{
if (m_flags & cFlagLinearChromaFiltering)
H2V1ConvertFiltered();
else
H2V1Convert();
*pScan_line = m_pScan_line_0;
break;
}
case JPGD_YH1V2:
{
if (chroma_y_filtering)
{
H1V2ConvertFiltered();
*pScan_line = m_pScan_line_0;
}
else
{
if ((m_mcu_lines_left & 1) == 0)
{
H1V2Convert();
*pScan_line = m_pScan_line_0;
}
else
*pScan_line = m_pScan_line_1;
}
break;
}
case JPGD_YH1V1:
{
H1V1Convert();
*pScan_line = m_pScan_line_0;
break;
}
case JPGD_GRAYSCALE:
{
gray_convert();
*pScan_line = m_pScan_line_0;
break;
}
}
*pScan_line_len = m_real_dest_bytes_per_scan_line;
if (!got_mcu_early)
{
m_mcu_lines_left--;
}
m_total_lines_left--;
return JPGD_SUCCESS;
}
// Creates the tables needed for efficient Huffman decoding.
void jpeg_decoder::make_huff_table(int index, huff_tables* pH)
{
int p, i, l, si;
uint8 huffsize[258];
uint huffcode[258];
uint code;
uint subtree;
int code_size;
int lastp;
int nextfreeentry;
int currententry;
pH->ac_table = m_huff_ac[index] != 0;
p = 0;
for (l = 1; l <= 16; l++)
{
for (i = 1; i <= m_huff_num[index][l]; i++)
{
if (p >= 257)
stop_decoding(JPGD_DECODE_ERROR);
huffsize[p++] = static_cast<uint8>(l);
}
}
assert(p < 258);
huffsize[p] = 0;
lastp = p;
code = 0;
si = huffsize[0];
p = 0;
while (huffsize[p])
{
while (huffsize[p] == si)
{
if (p >= 257)
stop_decoding(JPGD_DECODE_ERROR);
huffcode[p++] = code;
code++;
}
code <<= 1;
si++;
}
memset(pH->look_up, 0, sizeof(pH->look_up));
memset(pH->look_up2, 0, sizeof(pH->look_up2));
memset(pH->tree, 0, sizeof(pH->tree));
memset(pH->code_size, 0, sizeof(pH->code_size));
nextfreeentry = -1;
p = 0;
while (p < lastp)
{
i = m_huff_val[index][p];
code = huffcode[p];
code_size = huffsize[p];
assert(i < JPGD_HUFF_CODE_SIZE_MAX_LENGTH);
pH->code_size[i] = static_cast<uint8>(code_size);
if (code_size <= 8)
{
code <<= (8 - code_size);
for (l = 1 << (8 - code_size); l > 0; l--)
{
if (code >= 256)
stop_decoding(JPGD_DECODE_ERROR);
pH->look_up[code] = i;
bool has_extrabits = false;
int extra_bits = 0;
int num_extra_bits = i & 15;
int bits_to_fetch = code_size;
if (num_extra_bits)
{
int total_codesize = code_size + num_extra_bits;
if (total_codesize <= 8)
{
has_extrabits = true;
extra_bits = ((1 << num_extra_bits) - 1) & (code >> (8 - total_codesize));
if (extra_bits > 0x7FFF)
stop_decoding(JPGD_DECODE_ERROR);
bits_to_fetch += num_extra_bits;
}
}
if (!has_extrabits)
pH->look_up2[code] = i | (bits_to_fetch << 8);
else
pH->look_up2[code] = i | 0x8000 | (extra_bits << 16) | (bits_to_fetch << 8);
code++;
}
}
else
{
subtree = (code >> (code_size - 8)) & 0xFF;
currententry = pH->look_up[subtree];
if (currententry == 0)
{
pH->look_up[subtree] = currententry = nextfreeentry;
pH->look_up2[subtree] = currententry = nextfreeentry;
nextfreeentry -= 2;
}
code <<= (16 - (code_size - 8));
for (l = code_size; l > 9; l--)
{
if ((code & 0x8000) == 0)
currententry--;
unsigned int idx = -currententry - 1;
if (idx >= JPGD_HUFF_TREE_MAX_LENGTH)
stop_decoding(JPGD_DECODE_ERROR);
if (pH->tree[idx] == 0)
{
pH->tree[idx] = nextfreeentry;
currententry = nextfreeentry;
nextfreeentry -= 2;
}
else
{
currententry = pH->tree[idx];
}
code <<= 1;
}
if ((code & 0x8000) == 0)
currententry--;
if ((-currententry - 1) >= JPGD_HUFF_TREE_MAX_LENGTH)
stop_decoding(JPGD_DECODE_ERROR);
pH->tree[-currententry - 1] = i;
}
p++;
}
}
// Verifies the quantization tables needed for this scan are available.
void jpeg_decoder::check_quant_tables()
{
for (int i = 0; i < m_comps_in_scan; i++)
if (m_quant[m_comp_quant[m_comp_list[i]]] == nullptr)
stop_decoding(JPGD_UNDEFINED_QUANT_TABLE);
}
// Verifies that all the Huffman tables needed for this scan are available.
void jpeg_decoder::check_huff_tables()
{
for (int i = 0; i < m_comps_in_scan; i++)
{
if ((m_spectral_start == 0) && (m_huff_num[m_comp_dc_tab[m_comp_list[i]]] == nullptr))
stop_decoding(JPGD_UNDEFINED_HUFF_TABLE);
if ((m_spectral_end > 0) && (m_huff_num[m_comp_ac_tab[m_comp_list[i]]] == nullptr))
stop_decoding(JPGD_UNDEFINED_HUFF_TABLE);
}
for (int i = 0; i < JPGD_MAX_HUFF_TABLES; i++)
if (m_huff_num[i])
{
if (!m_pHuff_tabs[i])
m_pHuff_tabs[i] = (huff_tables*)alloc(sizeof(huff_tables));
make_huff_table(i, m_pHuff_tabs[i]);
}
}
// Determines the component order inside each MCU.
// Also calcs how many MCU's are on each row, etc.
bool jpeg_decoder::calc_mcu_block_order()
{
int component_num, component_id;
int max_h_samp = 0, max_v_samp = 0;
for (component_id = 0; component_id < m_comps_in_frame; component_id++)
{
if (m_comp_h_samp[component_id] > max_h_samp)
max_h_samp = m_comp_h_samp[component_id];
if (m_comp_v_samp[component_id] > max_v_samp)
max_v_samp = m_comp_v_samp[component_id];
}
for (component_id = 0; component_id < m_comps_in_frame; component_id++)
{
m_comp_h_blocks[component_id] = ((((m_image_x_size * m_comp_h_samp[component_id]) + (max_h_samp - 1)) / max_h_samp) + 7) / 8;
m_comp_v_blocks[component_id] = ((((m_image_y_size * m_comp_v_samp[component_id]) + (max_v_samp - 1)) / max_v_samp) + 7) / 8;
}
if (m_comps_in_scan == 1)
{
m_mcus_per_row = m_comp_h_blocks[m_comp_list[0]];
m_mcus_per_col = m_comp_v_blocks[m_comp_list[0]];
}
else
{
m_mcus_per_row = (((m_image_x_size + 7) / 8) + (max_h_samp - 1)) / max_h_samp;
m_mcus_per_col = (((m_image_y_size + 7) / 8) + (max_v_samp - 1)) / max_v_samp;
}
if (m_comps_in_scan == 1)
{
m_mcu_org[0] = m_comp_list[0];
m_blocks_per_mcu = 1;
}
else
{
m_blocks_per_mcu = 0;
for (component_num = 0; component_num < m_comps_in_scan; component_num++)
{
int num_blocks;