Fixing tabs
diff --git a/spec/basis_spec.txt b/spec/basis_spec.txt
index 7695de6..93ec749 100644
--- a/spec/basis_spec.txt
+++ b/spec/basis_spec.txt
@@ -213,41 +213,41 @@
enum
{
- // Max supported Huffman code size is 16-bits
- cHuffmanMaxSupportedCodeSize = 16,
+ // Max supported Huffman code size is 16-bits
+ cHuffmanMaxSupportedCodeSize = 16,
- // The maximum number of symbols is 2^14
- cHuffmanMaxSymsLog2 = 14,
- cHuffmanMaxSyms = 1 << cHuffmanMaxSymsLog2,
+ // The maximum number of symbols is 2^14
+ cHuffmanMaxSymsLog2 = 14,
+ cHuffmanMaxSyms = 1 << cHuffmanMaxSymsLog2,
- // Small zero runs may range from 3-10 entries
- cHuffmanSmallZeroRunSizeMin = 3,
- cHuffmanSmallZeroRunSizeMax = 10,
- cHuffmanSmallZeroRunExtraBits = 3,
+ // Small zero runs may range from 3-10 entries
+ cHuffmanSmallZeroRunSizeMin = 3,
+ cHuffmanSmallZeroRunSizeMax = 10,
+ cHuffmanSmallZeroRunExtraBits = 3,
- // Big zero runs may range from 11-138 entries
- cHuffmanBigZeroRunSizeMin = 11,
- cHuffmanBigZeroRunSizeMax = 138,
- cHuffmanBigZeroRunExtraBits = 7,
+ // Big zero runs may range from 11-138 entries
+ cHuffmanBigZeroRunSizeMin = 11,
+ cHuffmanBigZeroRunSizeMax = 138,
+ cHuffmanBigZeroRunExtraBits = 7,
- // Small non-zero runs may range from 3-6 entries
- cHuffmanSmallRepeatSizeMin = 3,
- cHuffmanSmallRepeatSizeMax = 6,
- cHuffmanSmallRepeatExtraBits = 2,
+ // Small non-zero runs may range from 3-6 entries
+ cHuffmanSmallRepeatSizeMin = 3,
+ cHuffmanSmallRepeatSizeMax = 6,
+ cHuffmanSmallRepeatExtraBits = 2,
- // Big non-zero run may range from 7-134 entries
- cHuffmanBigRepeatSizeMin = 7,
- cHuffmanBigRepeatSizeMax = 134,
- cHuffmanBigRepeatExtraBits = 7,
+ // Big non-zero run may range from 7-134 entries
+ cHuffmanBigRepeatSizeMin = 7,
+ cHuffmanBigRepeatSizeMax = 134,
+ cHuffmanBigRepeatExtraBits = 7,
- // There are a maximum of 21 symbols in a compressed Huffman code length table.
- cHuffmanTotalCodelengthCodes = 21,
-
- // Symbols [0,16] indicate code sizes. Other symbols indicate zero runs or repeats:
- cHuffmanSmallZeroRunCode = 17,
- cHuffmanBigZeroRunCode = 18,
- cHuffmanSmallRepeatCode = 19,
- cHuffmanBigRepeatCode = 20
+ // There are a maximum of 21 symbols in a compressed Huffman code length table.
+ cHuffmanTotalCodelengthCodes = 21,
+
+ // Symbols [0,16] indicate code sizes. Other symbols indicate zero runs or repeats:
+ cHuffmanSmallZeroRunCode = 17,
+ cHuffmanBigZeroRunCode = 18,
+ cHuffmanSmallRepeatCode = 19,
+ cHuffmanBigRepeatCode = 20
};
A .basis Huffman table consists of 1 to cHuffmanMaxSyms symbols. Each compressed
@@ -257,43 +257,43 @@
Deflate. (Note this can be confusing to developers unfamiliar with Deflate.)
Each table begins with a small fixed header:
- 14 bits: total_used_syms [1, cHuffmanMaxSyms]
- 5 bits: num_codelength_codes [1, cHuffmanTotalCodelengthCodes]
-
-Next, the code lengths for the small Huffman table which is used to send the compressed codelengths (and RLE/repeat codes) are sent uncompressed but in a reordered manner:
-
- 3*num_codelength_codes bits: Code size of each Huffman symbol for the compressed Huffman codelength table.
+ 14 bits: total_used_syms [1, cHuffmanMaxSyms]
+ 5 bits: num_codelength_codes [1, cHuffmanTotalCodelengthCodes]
- These code lengths are sent in this order (to help reduce the number that must be sent):
-
- {
- cHuffmanSmallZeroRunCode, cHuffmanBigZeroRunCode, cHuffmanSmallRepeatCode, cHuffmanBigRepeatCode,
- 0, 8, 7, 9, 6, 0xA, 5, 0xB, 4, 0xC, 3, 0xD, 2, 0xE, 1, 0xF, 0x10
- };
-
+Next, the code lengths for the small Huffman table which is used to send the compressed codelengths (and RLE/repeat codes) are sent uncompressed but in a reordered manner:
+
+ 3*num_codelength_codes bits: Code size of each Huffman symbol for the compressed Huffman codelength table.
+
+ These code lengths are sent in this order (to help reduce the number that must be sent):
+
+ {
+ cHuffmanSmallZeroRunCode, cHuffmanBigZeroRunCode, cHuffmanSmallRepeatCode, cHuffmanBigRepeatCode,
+ 0, 8, 7, 9, 6, 0xA, 5, 0xB, 4, 0xC, 3, 0xD, 2, 0xE, 1, 0xF, 0x10
+ };
+
A canonical Huffman decoding table (of up to 21 symbols) should be built from
these code lengths. Immediately following this data are the Huffman symbols
(sometimes intermixed with raw bits) which describe how to unpack the
codelengths of each symbol in the Huffman table:
- - Symbols [0,16] indicate a specific symbol code length in bits.
-
- - Symbol cHuffmanSmallZeroRunCode (17) indicates a short run of symbols with 0 bit code lengths.
- cHuffmanSmallZeroRunExtraBits (3) bits are sent after this symbol, which indicates the run's size after adding the minimum size (cHuffmanSmallZeroRunSizeMin).
-
- - Symbol cHuffmanBigZeroRunCode (18) indicates a long run of symbols with 0 bit code lengths.
- cHuffmanBigZeroRunExtraBits (7) bits are sent after this symbol, which indicates the run's size after adding the minimum size (cHuffmanBigZeroRunSizeMin)
+ - Symbols [0,16] indicate a specific symbol code length in bits.
+
+ - Symbol cHuffmanSmallZeroRunCode (17) indicates a short run of symbols with 0 bit code lengths.
+ cHuffmanSmallZeroRunExtraBits (3) bits are sent after this symbol, which indicates the run's size after adding the minimum size (cHuffmanSmallZeroRunSizeMin).
+
+ - Symbol cHuffmanBigZeroRunCode (18) indicates a long run of symbols with 0 bit code lengths.
+ cHuffmanBigZeroRunExtraBits (7) bits are sent after this symbol, which indicates the run's size after adding the minimum size (cHuffmanBigZeroRunSizeMin)
- - Symbol cHuffmanSmallRepeatCode (19) indicates a short run of symbols that repeat the previous symbol's code length.
- cHuffmanSmallRepeatExtraBits (2) bits are sent after this symbol, which indicates the number of times to repeat the previous symbol's code length,
- after adding the minimum size (cHuffmanSmallRepeatSizeMin).
- Cannot be the first symbol, and the previous symbol cannot have a code length of 0.
-
- - Symbol cHuffmanBigRepeatCode (20) indicates a short run of symbols that repeat the previous symbol's code length.
- cHuffmanBigRepeatExtraBits (7) bits are sent after this symbol, which indicates the number of times to repeat the previous symbol's code length,
- after adding the minimum size (cHuffmanBigRepeatSizeMin).
- Cannot be the first symbol, and the previous symbol cannot have a code length of 0.
-
+ - Symbol cHuffmanSmallRepeatCode (19) indicates a short run of symbols that repeat the previous symbol's code length.
+ cHuffmanSmallRepeatExtraBits (2) bits are sent after this symbol, which indicates the number of times to repeat the previous symbol's code length,
+ after adding the minimum size (cHuffmanSmallRepeatSizeMin).
+ Cannot be the first symbol, and the previous symbol cannot have a code length of 0.
+
+ - Symbol cHuffmanBigRepeatCode (20) indicates a short run of symbols that repeat the previous symbol's code length.
+ cHuffmanBigRepeatExtraBits (7) bits are sent after this symbol, which indicates the number of times to repeat the previous symbol's code length,
+ after adding the minimum size (cHuffmanBigRepeatSizeMin).
+ Cannot be the first symbol, and the previous symbol cannot have a code length of 0.
+
There should be exactly total_used_syms code lengths stored in the compressed Huffman table. If not the stream is either corrupted or invalid.
After all the symbol codelengths are uncompressed, the symbol codes can be computed and the canonical Huffman decoding tables can be built.
@@ -310,10 +310,10 @@
Huffman tables, stored using the procedure outlined in section 6.0. The Huffman tables
appear in this order:
- 1. color5_delta_model0
- 2. color5_delta_model1
- 3. color5_delta_model2
- 4. inten_delta_model
+ 1. color5_delta_model0
+ 2. color5_delta_model1
+ 3. color5_delta_model2
+ 4. inten_delta_model
Following the data for these Huffman tables is a single 1-bit code which
indicates if the color endpoint codebook is grayscale or not.
@@ -322,49 +322,49 @@
A simple form of DPCM coding is used to send the ETC1S intensity table indices and
color values. Here is the procedure to decode the endpoint codebook:
- const int COLOR5_PAL0_PREV_HI = 9, COLOR5_PAL0_DELTA_LO = -9, COLOR5_PAL0_DELTA_HI = 31;
- const int COLOR5_PAL1_PREV_HI = 21, COLOR5_PAL1_DELTA_LO = -21, COLOR5_PAL1_DELTA_HI = 21;
- const int COLOR5_PAL2_PREV_HI = 31, COLOR5_PAL2_DELTA_LO = -31, COLOR5_PAL2_DELTA_HI = 9;
+ const int COLOR5_PAL0_PREV_HI = 9, COLOR5_PAL0_DELTA_LO = -9, COLOR5_PAL0_DELTA_HI = 31;
+ const int COLOR5_PAL1_PREV_HI = 21, COLOR5_PAL1_DELTA_LO = -21, COLOR5_PAL1_DELTA_HI = 21;
+ const int COLOR5_PAL2_PREV_HI = 31, COLOR5_PAL2_DELTA_LO = -31, COLOR5_PAL2_DELTA_HI = 9;
- // Assume previous endpoint color is (16, 16, 16), and the previous intensity is 0.
- color32 prev_color5(16, 16, 16, 0);
- uint32_t prev_inten = 0;
+ // Assume previous endpoint color is (16, 16, 16), and the previous intensity is 0.
+ color32 prev_color5(16, 16, 16, 0);
+ uint32_t prev_inten = 0;
- // For each endpoint codebook entry
- for (uint32_t i = 0; i < num_endpoints; i++)
- {
- // Decode the intensity delta Huffman code
- uint32_t inten_delta = sym_codec.decode_huffman(inten_delta_model);
- m_endpoints[i].m_inten5 = static_cast<uint8_t>((inten_delta + prev_inten) & 7);
- prev_inten = m_endpoints[i].m_inten5;
+ // For each endpoint codebook entry
+ for (uint32_t i = 0; i < num_endpoints; i++)
+ {
+ // Decode the intensity delta Huffman code
+ uint32_t inten_delta = sym_codec.decode_huffman(inten_delta_model);
+ m_endpoints[i].m_inten5 = static_cast<uint8_t>((inten_delta + prev_inten) & 7);
+ prev_inten = m_endpoints[i].m_inten5;
- // Now decode the endpoint entry's color or intensity value
- for (uint32_t c = 0; c < (endpoints_are_grayscale ? 1U : 3U); c++)
- {
- // The Huffman table we used to decode the delta depends on the previous color's value
- int delta;
- if (prev_color5[c] <= basist::COLOR5_PAL0_PREV_HI)
- delta = sym_codec.decode_huffman(color5_delta_model0);
- else if (prev_color5[c] <= basist::COLOR5_PAL1_PREV_HI)
- delta = sym_codec.decode_huffman(color5_delta_model1);
- else
- delta = sym_codec.decode_huffman(color5_delta_model2);
+ // Now decode the endpoint entry's color or intensity value
+ for (uint32_t c = 0; c < (endpoints_are_grayscale ? 1U : 3U); c++)
+ {
+ // The Huffman table we used to decode the delta depends on the previous color's value
+ int delta;
+ if (prev_color5[c] <= basist::COLOR5_PAL0_PREV_HI)
+ delta = sym_codec.decode_huffman(color5_delta_model0);
+ else if (prev_color5[c] <= basist::COLOR5_PAL1_PREV_HI)
+ delta = sym_codec.decode_huffman(color5_delta_model1);
+ else
+ delta = sym_codec.decode_huffman(color5_delta_model2);
- // Apply the delta
- int v = (prev_color5[c] + delta) & 31;
+ // Apply the delta
+ int v = (prev_color5[c] + delta) & 31;
- m_endpoints[i].m_color5[c] = static_cast<uint8_t>(v);
+ m_endpoints[i].m_color5[c] = static_cast<uint8_t>(v);
- prev_color5[c] = static_cast<uint8_t>(v);
- }
+ prev_color5[c] = static_cast<uint8_t>(v);
+ }
- // If the endpoints are grayscale, set G and B to match R.
- if (endpoints_are_grayscale)
- {
- m_endpoints[i].m_color5[1] = m_endpoints[i].m_color5[0];
- m_endpoints[i].m_color5[2] = m_endpoints[i].m_color5[0];
- }
- }
+ // If the endpoints are grayscale, set G and B to match R.
+ if (endpoints_are_grayscale)
+ {
+ m_endpoints[i].m_color5[1] = m_endpoints[i].m_color5[0];
+ m_endpoints[i].m_color5[2] = m_endpoints[i].m_color5[0];
+ }
+ }
The rest of the section's data (if any) can be ignored.
