| /* |
| * jccolext-neon.c - colorspace conversion (32-bit Arm Neon) |
| * |
| * Copyright (C) 2020, Arm Limited. All Rights Reserved. |
| * Copyright (C) 2020, D. R. Commander. All Rights Reserved. |
| * |
| * This software is provided 'as-is', without any express or implied |
| * warranty. In no event will the authors be held liable for any damages |
| * arising from the use of this software. |
| * |
| * Permission is granted to anyone to use this software for any purpose, |
| * including commercial applications, and to alter it and redistribute it |
| * freely, subject to the following restrictions: |
| * |
| * 1. The origin of this software must not be misrepresented; you must not |
| * claim that you wrote the original software. If you use this software |
| * in a product, an acknowledgment in the product documentation would be |
| * appreciated but is not required. |
| * 2. Altered source versions must be plainly marked as such, and must not be |
| * misrepresented as being the original software. |
| * 3. This notice may not be removed or altered from any source distribution. |
| */ |
| |
| /* This file is included by jccolor-neon.c */ |
| |
| |
| /* RGB -> YCbCr conversion is defined by the following equations: |
| * Y = 0.29900 * R + 0.58700 * G + 0.11400 * B |
| * Cb = -0.16874 * R - 0.33126 * G + 0.50000 * B + 128 |
| * Cr = 0.50000 * R - 0.41869 * G - 0.08131 * B + 128 |
| * |
| * Avoid floating point arithmetic by using shifted integer constants: |
| * 0.29899597 = 19595 * 2^-16 |
| * 0.58700561 = 38470 * 2^-16 |
| * 0.11399841 = 7471 * 2^-16 |
| * 0.16874695 = 11059 * 2^-16 |
| * 0.33125305 = 21709 * 2^-16 |
| * 0.50000000 = 32768 * 2^-16 |
| * 0.41868592 = 27439 * 2^-16 |
| * 0.08131409 = 5329 * 2^-16 |
| * These constants are defined in jccolor-neon.c |
| * |
| * We add the fixed-point equivalent of 0.5 to Cb and Cr, which effectively |
| * rounds up or down the result via integer truncation. |
| */ |
| |
| void jsimd_rgb_ycc_convert_neon(JDIMENSION image_width, JSAMPARRAY input_buf, |
| JSAMPIMAGE output_buf, JDIMENSION output_row, |
| int num_rows) |
| { |
| /* Pointer to RGB(X/A) input data */ |
| JSAMPROW inptr; |
| /* Pointers to Y, Cb, and Cr output data */ |
| JSAMPROW outptr0, outptr1, outptr2; |
| |
| /* Set up conversion constants. */ |
| #ifdef HAVE_VLD1_U16_X2 |
| const uint16x4x2_t consts = vld1_u16_x2(jsimd_rgb_ycc_neon_consts); |
| #else |
| /* GCC does not currently support the intrinsic vld1_<type>_x2(). */ |
| const uint16x4_t consts1 = vld1_u16(jsimd_rgb_ycc_neon_consts); |
| const uint16x4_t consts2 = vld1_u16(jsimd_rgb_ycc_neon_consts + 4); |
| const uint16x4x2_t consts = { { consts1, consts2 } }; |
| #endif |
| const uint32x4_t scaled_128_5 = vdupq_n_u32((128 << 16) + 32767); |
| |
| while (--num_rows >= 0) { |
| inptr = *input_buf++; |
| outptr0 = output_buf[0][output_row]; |
| outptr1 = output_buf[1][output_row]; |
| outptr2 = output_buf[2][output_row]; |
| output_row++; |
| |
| int cols_remaining = image_width; |
| for (; cols_remaining > 0; cols_remaining -= 8) { |
| |
| /* To prevent buffer overread by the vector load instructions, the last |
| * (image_width % 8) columns of data are first memcopied to a temporary |
| * buffer large enough to accommodate the vector load. |
| */ |
| if (cols_remaining < 8) { |
| ALIGN(16) uint8_t tmp_buf[8 * RGB_PIXELSIZE]; |
| memcpy(tmp_buf, inptr, cols_remaining * RGB_PIXELSIZE); |
| inptr = tmp_buf; |
| } |
| |
| #if RGB_PIXELSIZE == 4 |
| uint8x8x4_t input_pixels = vld4_u8(inptr); |
| #else |
| uint8x8x3_t input_pixels = vld3_u8(inptr); |
| #endif |
| uint16x8_t r = vmovl_u8(input_pixels.val[RGB_RED]); |
| uint16x8_t g = vmovl_u8(input_pixels.val[RGB_GREEN]); |
| uint16x8_t b = vmovl_u8(input_pixels.val[RGB_BLUE]); |
| |
| /* Compute Y = 0.29900 * R + 0.58700 * G + 0.11400 * B */ |
| uint32x4_t y_low = vmull_lane_u16(vget_low_u16(r), consts.val[0], 0); |
| y_low = vmlal_lane_u16(y_low, vget_low_u16(g), consts.val[0], 1); |
| y_low = vmlal_lane_u16(y_low, vget_low_u16(b), consts.val[0], 2); |
| uint32x4_t y_high = vmull_lane_u16(vget_high_u16(r), consts.val[0], 0); |
| y_high = vmlal_lane_u16(y_high, vget_high_u16(g), consts.val[0], 1); |
| y_high = vmlal_lane_u16(y_high, vget_high_u16(b), consts.val[0], 2); |
| |
| /* Compute Cb = -0.16874 * R - 0.33126 * G + 0.50000 * B + 128 */ |
| uint32x4_t cb_low = scaled_128_5; |
| cb_low = vmlsl_lane_u16(cb_low, vget_low_u16(r), consts.val[0], 3); |
| cb_low = vmlsl_lane_u16(cb_low, vget_low_u16(g), consts.val[1], 0); |
| cb_low = vmlal_lane_u16(cb_low, vget_low_u16(b), consts.val[1], 1); |
| uint32x4_t cb_high = scaled_128_5; |
| cb_high = vmlsl_lane_u16(cb_high, vget_high_u16(r), consts.val[0], 3); |
| cb_high = vmlsl_lane_u16(cb_high, vget_high_u16(g), consts.val[1], 0); |
| cb_high = vmlal_lane_u16(cb_high, vget_high_u16(b), consts.val[1], 1); |
| |
| /* Compute Cr = 0.50000 * R - 0.41869 * G - 0.08131 * B + 128 */ |
| uint32x4_t cr_low = scaled_128_5; |
| cr_low = vmlal_lane_u16(cr_low, vget_low_u16(r), consts.val[1], 1); |
| cr_low = vmlsl_lane_u16(cr_low, vget_low_u16(g), consts.val[1], 2); |
| cr_low = vmlsl_lane_u16(cr_low, vget_low_u16(b), consts.val[1], 3); |
| uint32x4_t cr_high = scaled_128_5; |
| cr_high = vmlal_lane_u16(cr_high, vget_high_u16(r), consts.val[1], 1); |
| cr_high = vmlsl_lane_u16(cr_high, vget_high_u16(g), consts.val[1], 2); |
| cr_high = vmlsl_lane_u16(cr_high, vget_high_u16(b), consts.val[1], 3); |
| |
| /* Descale Y values (rounding right shift) and narrow to 16-bit. */ |
| uint16x8_t y_u16 = vcombine_u16(vrshrn_n_u32(y_low, 16), |
| vrshrn_n_u32(y_high, 16)); |
| /* Descale Cb values (right shift) and narrow to 16-bit. */ |
| uint16x8_t cb_u16 = vcombine_u16(vshrn_n_u32(cb_low, 16), |
| vshrn_n_u32(cb_high, 16)); |
| /* Descale Cr values (right shift) and narrow to 16-bit. */ |
| uint16x8_t cr_u16 = vcombine_u16(vshrn_n_u32(cr_low, 16), |
| vshrn_n_u32(cr_high, 16)); |
| /* Narrow Y, Cb, and Cr values to 8-bit and store to memory. Buffer |
| * overwrite is permitted up to the next multiple of ALIGN_SIZE bytes. |
| */ |
| vst1_u8(outptr0, vmovn_u16(y_u16)); |
| vst1_u8(outptr1, vmovn_u16(cb_u16)); |
| vst1_u8(outptr2, vmovn_u16(cr_u16)); |
| |
| /* Increment pointers. */ |
| inptr += (8 * RGB_PIXELSIZE); |
| outptr0 += 8; |
| outptr1 += 8; |
| outptr2 += 8; |
| } |
| } |
| } |
