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jdcolext-neon.c
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/*
* jdcolext-neon.c - colorspace conversion (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 jdcolor-neon.c. */
/* YCbCr -> RGB conversion is defined by the following equations:
* R = Y + 1.40200 * (Cr - 128)
* G = Y - 0.34414 * (Cb - 128) - 0.71414 * (Cr - 128)
* B = Y + 1.77200 * (Cb - 128)
*
* Scaled integer constants are used to avoid floating-point arithmetic:
* 0.3441467 = 11277 * 2^-15
* 0.7141418 = 23401 * 2^-15
* 1.4020386 = 22971 * 2^-14
* 1.7720337 = 29033 * 2^-14
* These constants are defined in jdcolor-neon.c.
*
* To ensure correct results, rounding is used when descaling.
*/
/* Notes on safe memory access for YCbCr -> RGB conversion routines:
*
* Input memory buffers can be safely overread up to the next multiple of
* ALIGN_SIZE bytes, since they are always allocated by alloc_sarray() in
* jmemmgr.c.
*
* The output buffer cannot safely be written beyond output_width, since
* output_buf points to a possibly unpadded row in the decompressed image
* buffer allocated by the calling program.
*/
void jsimd_ycc_rgb_convert_neon(JDIMENSION output_width, JSAMPIMAGE input_buf,
JDIMENSION input_row, JSAMPARRAY output_buf,
int num_rows)
{
JSAMPROW outptr;
/* Pointers to Y, Cb, and Cr data */
JSAMPROW inptr0, inptr1, inptr2;
const int16x4_t consts = vld1_s16(jsimd_ycc_rgb_convert_neon_consts);
const int16x8_t neg_128 = vdupq_n_s16(-128);
while (--num_rows >= 0) {
inptr0 = input_buf[0][input_row];
inptr1 = input_buf[1][input_row];
inptr2 = input_buf[2][input_row];
input_row++;
outptr = *output_buf++;
int cols_remaining = output_width;
for (; cols_remaining >= 16; cols_remaining -= 16) {
uint8x16_t y = vld1q_u8(inptr0);
uint8x16_t cb = vld1q_u8(inptr1);
uint8x16_t cr = vld1q_u8(inptr2);
/* Subtract 128 from Cb and Cr. */
int16x8_t cr_128_l =
vreinterpretq_s16_u16(vaddw_u8(vreinterpretq_u16_s16(neg_128),
vget_low_u8(cr)));
int16x8_t cr_128_h =
vreinterpretq_s16_u16(vaddw_u8(vreinterpretq_u16_s16(neg_128),
vget_high_u8(cr)));
int16x8_t cb_128_l =
vreinterpretq_s16_u16(vaddw_u8(vreinterpretq_u16_s16(neg_128),
vget_low_u8(cb)));
int16x8_t cb_128_h =
vreinterpretq_s16_u16(vaddw_u8(vreinterpretq_u16_s16(neg_128),
vget_high_u8(cb)));
/* Compute G-Y: - 0.34414 * (Cb - 128) - 0.71414 * (Cr - 128) */
int32x4_t g_sub_y_ll = vmull_lane_s16(vget_low_s16(cb_128_l), consts, 0);
int32x4_t g_sub_y_lh = vmull_lane_s16(vget_high_s16(cb_128_l),
consts, 0);
int32x4_t g_sub_y_hl = vmull_lane_s16(vget_low_s16(cb_128_h), consts, 0);
int32x4_t g_sub_y_hh = vmull_lane_s16(vget_high_s16(cb_128_h),
consts, 0);
g_sub_y_ll = vmlsl_lane_s16(g_sub_y_ll, vget_low_s16(cr_128_l),
consts, 1);
g_sub_y_lh = vmlsl_lane_s16(g_sub_y_lh, vget_high_s16(cr_128_l),
consts, 1);
g_sub_y_hl = vmlsl_lane_s16(g_sub_y_hl, vget_low_s16(cr_128_h),
consts, 1);
g_sub_y_hh = vmlsl_lane_s16(g_sub_y_hh, vget_high_s16(cr_128_h),
consts, 1);
/* Descale G components: shift right 15, round, and narrow to 16-bit. */
int16x8_t g_sub_y_l = vcombine_s16(vrshrn_n_s32(g_sub_y_ll, 15),
vrshrn_n_s32(g_sub_y_lh, 15));
int16x8_t g_sub_y_h = vcombine_s16(vrshrn_n_s32(g_sub_y_hl, 15),
vrshrn_n_s32(g_sub_y_hh, 15));
/* Compute R-Y: 1.40200 * (Cr - 128) */
int16x8_t r_sub_y_l = vqrdmulhq_lane_s16(vshlq_n_s16(cr_128_l, 1),
consts, 2);
int16x8_t r_sub_y_h = vqrdmulhq_lane_s16(vshlq_n_s16(cr_128_h, 1),
consts, 2);
/* Compute B-Y: 1.77200 * (Cb - 128) */
int16x8_t b_sub_y_l = vqrdmulhq_lane_s16(vshlq_n_s16(cb_128_l, 1),
consts, 3);
int16x8_t b_sub_y_h = vqrdmulhq_lane_s16(vshlq_n_s16(cb_128_h, 1),
consts, 3);
/* Add Y. */
int16x8_t r_l =
vreinterpretq_s16_u16(vaddw_u8(vreinterpretq_u16_s16(r_sub_y_l),
vget_low_u8(y)));
int16x8_t r_h =
vreinterpretq_s16_u16(vaddw_u8(vreinterpretq_u16_s16(r_sub_y_h),
vget_high_u8(y)));
int16x8_t b_l =
vreinterpretq_s16_u16(vaddw_u8(vreinterpretq_u16_s16(b_sub_y_l),
vget_low_u8(y)));
int16x8_t b_h =
vreinterpretq_s16_u16(vaddw_u8(vreinterpretq_u16_s16(b_sub_y_h),
vget_high_u8(y)));
int16x8_t g_l =
vreinterpretq_s16_u16(vaddw_u8(vreinterpretq_u16_s16(g_sub_y_l),
vget_low_u8(y)));
int16x8_t g_h =
vreinterpretq_s16_u16(vaddw_u8(vreinterpretq_u16_s16(g_sub_y_h),
vget_high_u8(y)));
#if RGB_PIXELSIZE == 4
uint8x16x4_t rgba;
/* Convert each component to unsigned and narrow, clamping to [0-255]. */
rgba.val[RGB_RED] = vcombine_u8(vqmovun_s16(r_l), vqmovun_s16(r_h));
rgba.val[RGB_GREEN] = vcombine_u8(vqmovun_s16(g_l), vqmovun_s16(g_h));
rgba.val[RGB_BLUE] = vcombine_u8(vqmovun_s16(b_l), vqmovun_s16(b_h));
/* Set alpha channel to opaque (0xFF). */
rgba.val[RGB_ALPHA] = vdupq_n_u8(0xFF);
/* Store RGBA pixel data to memory. */
vst4q_u8(outptr, rgba);
#elif RGB_PIXELSIZE == 3
uint8x16x3_t rgb;
/* Convert each component to unsigned and narrow, clamping to [0-255]. */
rgb.val[RGB_RED] = vcombine_u8(vqmovun_s16(r_l), vqmovun_s16(r_h));
rgb.val[RGB_GREEN] = vcombine_u8(vqmovun_s16(g_l), vqmovun_s16(g_h));
rgb.val[RGB_BLUE] = vcombine_u8(vqmovun_s16(b_l), vqmovun_s16(b_h));
/* Store RGB pixel data to memory. */
vst3q_u8(outptr, rgb);
#else
/* Pack R, G, and B values in ratio 5:6:5. */
uint16x8_t rgb565_l = vqshluq_n_s16(r_l, 8);
rgb565_l = vsriq_n_u16(rgb565_l, vqshluq_n_s16(g_l, 8), 5);
rgb565_l = vsriq_n_u16(rgb565_l, vqshluq_n_s16(b_l, 8), 11);
uint16x8_t rgb565_h = vqshluq_n_s16(r_h, 8);
rgb565_h = vsriq_n_u16(rgb565_h, vqshluq_n_s16(g_h, 8), 5);
rgb565_h = vsriq_n_u16(rgb565_h, vqshluq_n_s16(b_h, 8), 11);
/* Store RGB pixel data to memory. */
vst1q_u16((uint16_t *)outptr, rgb565_l);
vst1q_u16(((uint16_t *)outptr) + 8, rgb565_h);
#endif
/* Increment pointers. */
inptr0 += 16;
inptr1 += 16;
inptr2 += 16;
outptr += (RGB_PIXELSIZE * 16);
}
if (cols_remaining >= 8) {
uint8x8_t y = vld1_u8(inptr0);
uint8x8_t cb = vld1_u8(inptr1);
uint8x8_t cr = vld1_u8(inptr2);
/* Subtract 128 from Cb and Cr. */
int16x8_t cr_128 =
vreinterpretq_s16_u16(vaddw_u8(vreinterpretq_u16_s16(neg_128), cr));
int16x8_t cb_128 =
vreinterpretq_s16_u16(vaddw_u8(vreinterpretq_u16_s16(neg_128), cb));
/* Compute G-Y: - 0.34414 * (Cb - 128) - 0.71414 * (Cr - 128) */
int32x4_t g_sub_y_l = vmull_lane_s16(vget_low_s16(cb_128), consts, 0);
int32x4_t g_sub_y_h = vmull_lane_s16(vget_high_s16(cb_128), consts, 0);
g_sub_y_l = vmlsl_lane_s16(g_sub_y_l, vget_low_s16(cr_128), consts, 1);
g_sub_y_h = vmlsl_lane_s16(g_sub_y_h, vget_high_s16(cr_128), consts, 1);
/* Descale G components: shift right 15, round, and narrow to 16-bit. */
int16x8_t g_sub_y = vcombine_s16(vrshrn_n_s32(g_sub_y_l, 15),
vrshrn_n_s32(g_sub_y_h, 15));
/* Compute R-Y: 1.40200 * (Cr - 128) */
int16x8_t r_sub_y = vqrdmulhq_lane_s16(vshlq_n_s16(cr_128, 1),
consts, 2);
/* Compute B-Y: 1.77200 * (Cb - 128) */
int16x8_t b_sub_y = vqrdmulhq_lane_s16(vshlq_n_s16(cb_128, 1),
consts, 3);
/* Add Y. */
int16x8_t r =
vreinterpretq_s16_u16(vaddw_u8(vreinterpretq_u16_s16(r_sub_y), y));
int16x8_t b =
vreinterpretq_s16_u16(vaddw_u8(vreinterpretq_u16_s16(b_sub_y), y));
int16x8_t g =
vreinterpretq_s16_u16(vaddw_u8(vreinterpretq_u16_s16(g_sub_y), y));
#if RGB_PIXELSIZE == 4
uint8x8x4_t rgba;
/* Convert each component to unsigned and narrow, clamping to [0-255]. */
rgba.val[RGB_RED] = vqmovun_s16(r);
rgba.val[RGB_GREEN] = vqmovun_s16(g);
rgba.val[RGB_BLUE] = vqmovun_s16(b);
/* Set alpha channel to opaque (0xFF). */
rgba.val[RGB_ALPHA] = vdup_n_u8(0xFF);
/* Store RGBA pixel data to memory. */
vst4_u8(outptr, rgba);
#elif RGB_PIXELSIZE == 3
uint8x8x3_t rgb;
/* Convert each component to unsigned and narrow, clamping to [0-255]. */
rgb.val[RGB_RED] = vqmovun_s16(r);
rgb.val[RGB_GREEN] = vqmovun_s16(g);
rgb.val[RGB_BLUE] = vqmovun_s16(b);
/* Store RGB pixel data to memory. */
vst3_u8(outptr, rgb);
#else
/* Pack R, G, and B values in ratio 5:6:5. */
uint16x8_t rgb565 = vqshluq_n_s16(r, 8);
rgb565 = vsriq_n_u16(rgb565, vqshluq_n_s16(g, 8), 5);
rgb565 = vsriq_n_u16(rgb565, vqshluq_n_s16(b, 8), 11);
/* Store RGB pixel data to memory. */
vst1q_u16((uint16_t *)outptr, rgb565);
#endif
/* Increment pointers. */
inptr0 += 8;
inptr1 += 8;
inptr2 += 8;
outptr += (RGB_PIXELSIZE * 8);
cols_remaining -= 8;
}
/* Handle the tail elements. */
if (cols_remaining > 0) {
uint8x8_t y = vld1_u8(inptr0);
uint8x8_t cb = vld1_u8(inptr1);
uint8x8_t cr = vld1_u8(inptr2);
/* Subtract 128 from Cb and Cr. */
int16x8_t cr_128 =
vreinterpretq_s16_u16(vaddw_u8(vreinterpretq_u16_s16(neg_128), cr));
int16x8_t cb_128 =
vreinterpretq_s16_u16(vaddw_u8(vreinterpretq_u16_s16(neg_128), cb));
/* Compute G-Y: - 0.34414 * (Cb - 128) - 0.71414 * (Cr - 128) */
int32x4_t g_sub_y_l = vmull_lane_s16(vget_low_s16(cb_128), consts, 0);
int32x4_t g_sub_y_h = vmull_lane_s16(vget_high_s16(cb_128), consts, 0);
g_sub_y_l = vmlsl_lane_s16(g_sub_y_l, vget_low_s16(cr_128), consts, 1);
g_sub_y_h = vmlsl_lane_s16(g_sub_y_h, vget_high_s16(cr_128), consts, 1);
/* Descale G components: shift right 15, round, and narrow to 16-bit. */
int16x8_t g_sub_y = vcombine_s16(vrshrn_n_s32(g_sub_y_l, 15),
vrshrn_n_s32(g_sub_y_h, 15));
/* Compute R-Y: 1.40200 * (Cr - 128) */
int16x8_t r_sub_y = vqrdmulhq_lane_s16(vshlq_n_s16(cr_128, 1),
consts, 2);
/* Compute B-Y: 1.77200 * (Cb - 128) */
int16x8_t b_sub_y = vqrdmulhq_lane_s16(vshlq_n_s16(cb_128, 1),
consts, 3);
/* Add Y. */
int16x8_t r =
vreinterpretq_s16_u16(vaddw_u8(vreinterpretq_u16_s16(r_sub_y), y));
int16x8_t b =
vreinterpretq_s16_u16(vaddw_u8(vreinterpretq_u16_s16(b_sub_y), y));
int16x8_t g =
vreinterpretq_s16_u16(vaddw_u8(vreinterpretq_u16_s16(g_sub_y), y));
#if RGB_PIXELSIZE == 4
uint8x8x4_t rgba;
/* Convert each component to unsigned and narrow, clamping to [0-255]. */
rgba.val[RGB_RED] = vqmovun_s16(r);
rgba.val[RGB_GREEN] = vqmovun_s16(g);
rgba.val[RGB_BLUE] = vqmovun_s16(b);
/* Set alpha channel to opaque (0xFF). */
rgba.val[RGB_ALPHA] = vdup_n_u8(0xFF);
/* Store RGBA pixel data to memory. */
switch (cols_remaining) {
case 7:
vst4_lane_u8(outptr + 6 * RGB_PIXELSIZE, rgba, 6);
FALLTHROUGH /*FALLTHROUGH*/
case 6:
vst4_lane_u8(outptr + 5 * RGB_PIXELSIZE, rgba, 5);
FALLTHROUGH /*FALLTHROUGH*/
case 5:
vst4_lane_u8(outptr + 4 * RGB_PIXELSIZE, rgba, 4);
FALLTHROUGH /*FALLTHROUGH*/
case 4:
vst4_lane_u8(outptr + 3 * RGB_PIXELSIZE, rgba, 3);
FALLTHROUGH /*FALLTHROUGH*/
case 3:
vst4_lane_u8(outptr + 2 * RGB_PIXELSIZE, rgba, 2);
FALLTHROUGH /*FALLTHROUGH*/
case 2:
vst4_lane_u8(outptr + RGB_PIXELSIZE, rgba, 1);
FALLTHROUGH /*FALLTHROUGH*/
case 1:
vst4_lane_u8(outptr, rgba, 0);
FALLTHROUGH /*FALLTHROUGH*/
default:
break;
}
#elif RGB_PIXELSIZE == 3
uint8x8x3_t rgb;
/* Convert each component to unsigned and narrow, clamping to [0-255]. */
rgb.val[RGB_RED] = vqmovun_s16(r);
rgb.val[RGB_GREEN] = vqmovun_s16(g);
rgb.val[RGB_BLUE] = vqmovun_s16(b);
/* Store RGB pixel data to memory. */
switch (cols_remaining) {
case 7:
vst3_lane_u8(outptr + 6 * RGB_PIXELSIZE, rgb, 6);
FALLTHROUGH /*FALLTHROUGH*/
case 6:
vst3_lane_u8(outptr + 5 * RGB_PIXELSIZE, rgb, 5);
FALLTHROUGH /*FALLTHROUGH*/
case 5:
vst3_lane_u8(outptr + 4 * RGB_PIXELSIZE, rgb, 4);
FALLTHROUGH /*FALLTHROUGH*/
case 4:
vst3_lane_u8(outptr + 3 * RGB_PIXELSIZE, rgb, 3);
FALLTHROUGH /*FALLTHROUGH*/
case 3:
vst3_lane_u8(outptr + 2 * RGB_PIXELSIZE, rgb, 2);
FALLTHROUGH /*FALLTHROUGH*/
case 2:
vst3_lane_u8(outptr + RGB_PIXELSIZE, rgb, 1);
FALLTHROUGH /*FALLTHROUGH*/
case 1:
vst3_lane_u8(outptr, rgb, 0);
FALLTHROUGH /*FALLTHROUGH*/
default:
break;
}
#else
/* Pack R, G, and B values in ratio 5:6:5. */
uint16x8_t rgb565 = vqshluq_n_s16(r, 8);
rgb565 = vsriq_n_u16(rgb565, vqshluq_n_s16(g, 8), 5);
rgb565 = vsriq_n_u16(rgb565, vqshluq_n_s16(b, 8), 11);
/* Store RGB565 pixel data to memory. */
switch (cols_remaining) {
case 7:
vst1q_lane_u16((uint16_t *)(outptr + 6 * RGB_PIXELSIZE), rgb565, 6);
FALLTHROUGH /*FALLTHROUGH*/
case 6:
vst1q_lane_u16((uint16_t *)(outptr + 5 * RGB_PIXELSIZE), rgb565, 5);
FALLTHROUGH /*FALLTHROUGH*/
case 5:
vst1q_lane_u16((uint16_t *)(outptr + 4 * RGB_PIXELSIZE), rgb565, 4);
FALLTHROUGH /*FALLTHROUGH*/
case 4:
vst1q_lane_u16((uint16_t *)(outptr + 3 * RGB_PIXELSIZE), rgb565, 3);
FALLTHROUGH /*FALLTHROUGH*/
case 3:
vst1q_lane_u16((uint16_t *)(outptr + 2 * RGB_PIXELSIZE), rgb565, 2);
FALLTHROUGH /*FALLTHROUGH*/
case 2:
vst1q_lane_u16((uint16_t *)(outptr + RGB_PIXELSIZE), rgb565, 1);
FALLTHROUGH /*FALLTHROUGH*/
case 1:
vst1q_lane_u16((uint16_t *)outptr, rgb565, 0);
FALLTHROUGH /*FALLTHROUGH*/
default:
break;
}
#endif
}
}
}