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Diffstat (limited to 'media/libjpeg/simd/arm/jdsample-neon.c')
| -rw-r--r-- | media/libjpeg/simd/arm/jdsample-neon.c | 569 |
1 files changed, 569 insertions, 0 deletions
diff --git a/media/libjpeg/simd/arm/jdsample-neon.c b/media/libjpeg/simd/arm/jdsample-neon.c new file mode 100644 index 0000000000..90ec6782c4 --- /dev/null +++ b/media/libjpeg/simd/arm/jdsample-neon.c @@ -0,0 +1,569 @@ +/* + * jdsample-neon.c - upsampling (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. + */ + +#define JPEG_INTERNALS +#include "../../jinclude.h" +#include "../../jpeglib.h" +#include "../../jsimd.h" +#include "../../jdct.h" +#include "../../jsimddct.h" +#include "../jsimd.h" + +#include <arm_neon.h> + + +/* The diagram below shows a row of samples produced by h2v1 downsampling. + * + * s0 s1 s2 + * +---------+---------+---------+ + * | | | | + * | p0 p1 | p2 p3 | p4 p5 | + * | | | | + * +---------+---------+---------+ + * + * Samples s0-s2 were created by averaging the original pixel component values + * centered at positions p0-p5 above. To approximate those original pixel + * component values, we proportionally blend the adjacent samples in each row. + * + * An upsampled pixel component value is computed by blending the sample + * containing the pixel center with the nearest neighboring sample, in the + * ratio 3:1. For example: + * p1(upsampled) = 3/4 * s0 + 1/4 * s1 + * p2(upsampled) = 3/4 * s1 + 1/4 * s0 + * When computing the first and last pixel component values in the row, there + * is no adjacent sample to blend, so: + * p0(upsampled) = s0 + * p5(upsampled) = s2 + */ + +void jsimd_h2v1_fancy_upsample_neon(int max_v_samp_factor, + JDIMENSION downsampled_width, + JSAMPARRAY input_data, + JSAMPARRAY *output_data_ptr) +{ + JSAMPARRAY output_data = *output_data_ptr; + JSAMPROW inptr, outptr; + int inrow; + unsigned colctr; + /* Set up constants. */ + const uint16x8_t one_u16 = vdupq_n_u16(1); + const uint8x8_t three_u8 = vdup_n_u8(3); + + for (inrow = 0; inrow < max_v_samp_factor; inrow++) { + inptr = input_data[inrow]; + outptr = output_data[inrow]; + /* First pixel component value in this row of the original image */ + *outptr = (JSAMPLE)GETJSAMPLE(*inptr); + + /* 3/4 * containing sample + 1/4 * nearest neighboring sample + * For p1: containing sample = s0, nearest neighboring sample = s1 + * For p2: containing sample = s1, nearest neighboring sample = s0 + */ + uint8x16_t s0 = vld1q_u8(inptr); + uint8x16_t s1 = vld1q_u8(inptr + 1); + /* Multiplication makes vectors twice as wide. '_l' and '_h' suffixes + * denote low half and high half respectively. + */ + uint16x8_t s1_add_3s0_l = + vmlal_u8(vmovl_u8(vget_low_u8(s1)), vget_low_u8(s0), three_u8); + uint16x8_t s1_add_3s0_h = + vmlal_u8(vmovl_u8(vget_high_u8(s1)), vget_high_u8(s0), three_u8); + uint16x8_t s0_add_3s1_l = + vmlal_u8(vmovl_u8(vget_low_u8(s0)), vget_low_u8(s1), three_u8); + uint16x8_t s0_add_3s1_h = + vmlal_u8(vmovl_u8(vget_high_u8(s0)), vget_high_u8(s1), three_u8); + /* Add ordered dithering bias to odd pixel values. */ + s0_add_3s1_l = vaddq_u16(s0_add_3s1_l, one_u16); + s0_add_3s1_h = vaddq_u16(s0_add_3s1_h, one_u16); + + /* The offset is initially 1, because the first pixel component has already + * been stored. However, in subsequent iterations of the SIMD loop, this + * offset is (2 * colctr - 1) to stay within the bounds of the sample + * buffers without having to resort to a slow scalar tail case for the last + * (downsampled_width % 16) samples. See "Creation of 2-D sample arrays" + * in jmemmgr.c for more details. + */ + unsigned outptr_offset = 1; + uint8x16x2_t output_pixels; + + /* We use software pipelining to maximise performance. The code indented + * an extra two spaces begins the next iteration of the loop. + */ + for (colctr = 16; colctr < downsampled_width; colctr += 16) { + + s0 = vld1q_u8(inptr + colctr - 1); + s1 = vld1q_u8(inptr + colctr); + + /* Right-shift by 2 (divide by 4), narrow to 8-bit, and combine. */ + output_pixels.val[0] = vcombine_u8(vrshrn_n_u16(s1_add_3s0_l, 2), + vrshrn_n_u16(s1_add_3s0_h, 2)); + output_pixels.val[1] = vcombine_u8(vshrn_n_u16(s0_add_3s1_l, 2), + vshrn_n_u16(s0_add_3s1_h, 2)); + + /* Multiplication makes vectors twice as wide. '_l' and '_h' suffixes + * denote low half and high half respectively. + */ + s1_add_3s0_l = + vmlal_u8(vmovl_u8(vget_low_u8(s1)), vget_low_u8(s0), three_u8); + s1_add_3s0_h = + vmlal_u8(vmovl_u8(vget_high_u8(s1)), vget_high_u8(s0), three_u8); + s0_add_3s1_l = + vmlal_u8(vmovl_u8(vget_low_u8(s0)), vget_low_u8(s1), three_u8); + s0_add_3s1_h = + vmlal_u8(vmovl_u8(vget_high_u8(s0)), vget_high_u8(s1), three_u8); + /* Add ordered dithering bias to odd pixel values. */ + s0_add_3s1_l = vaddq_u16(s0_add_3s1_l, one_u16); + s0_add_3s1_h = vaddq_u16(s0_add_3s1_h, one_u16); + + /* Store pixel component values to memory. */ + vst2q_u8(outptr + outptr_offset, output_pixels); + outptr_offset = 2 * colctr - 1; + } + + /* Complete the last iteration of the loop. */ + + /* Right-shift by 2 (divide by 4), narrow to 8-bit, and combine. */ + output_pixels.val[0] = vcombine_u8(vrshrn_n_u16(s1_add_3s0_l, 2), + vrshrn_n_u16(s1_add_3s0_h, 2)); + output_pixels.val[1] = vcombine_u8(vshrn_n_u16(s0_add_3s1_l, 2), + vshrn_n_u16(s0_add_3s1_h, 2)); + /* Store pixel component values to memory. */ + vst2q_u8(outptr + outptr_offset, output_pixels); + + /* Last pixel component value in this row of the original image */ + outptr[2 * downsampled_width - 1] = + GETJSAMPLE(inptr[downsampled_width - 1]); + } +} + + +/* The diagram below shows an array of samples produced by h2v2 downsampling. + * + * s0 s1 s2 + * +---------+---------+---------+ + * | p0 p1 | p2 p3 | p4 p5 | + * sA | | | | + * | p6 p7 | p8 p9 | p10 p11| + * +---------+---------+---------+ + * | p12 p13| p14 p15| p16 p17| + * sB | | | | + * | p18 p19| p20 p21| p22 p23| + * +---------+---------+---------+ + * | p24 p25| p26 p27| p28 p29| + * sC | | | | + * | p30 p31| p32 p33| p34 p35| + * +---------+---------+---------+ + * + * Samples s0A-s2C were created by averaging the original pixel component + * values centered at positions p0-p35 above. To approximate one of those + * original pixel component values, we proportionally blend the sample + * containing the pixel center with the nearest neighboring samples in each + * row, column, and diagonal. + * + * An upsampled pixel component value is computed by first blending the sample + * containing the pixel center with the nearest neighboring samples in the + * same column, in the ratio 3:1, and then blending each column sum with the + * nearest neighboring column sum, in the ratio 3:1. For example: + * p14(upsampled) = 3/4 * (3/4 * s1B + 1/4 * s1A) + + * 1/4 * (3/4 * s0B + 1/4 * s0A) + * = 9/16 * s1B + 3/16 * s1A + 3/16 * s0B + 1/16 * s0A + * When computing the first and last pixel component values in the row, there + * is no horizontally adjacent sample to blend, so: + * p12(upsampled) = 3/4 * s0B + 1/4 * s0A + * p23(upsampled) = 3/4 * s2B + 1/4 * s2C + * When computing the first and last pixel component values in the column, + * there is no vertically adjacent sample to blend, so: + * p2(upsampled) = 3/4 * s1A + 1/4 * s0A + * p33(upsampled) = 3/4 * s1C + 1/4 * s2C + * When computing the corner pixel component values, there is no adjacent + * sample to blend, so: + * p0(upsampled) = s0A + * p35(upsampled) = s2C + */ + +void jsimd_h2v2_fancy_upsample_neon(int max_v_samp_factor, + JDIMENSION downsampled_width, + JSAMPARRAY input_data, + JSAMPARRAY *output_data_ptr) +{ + JSAMPARRAY output_data = *output_data_ptr; + JSAMPROW inptr0, inptr1, inptr2, outptr0, outptr1; + int inrow, outrow; + unsigned colctr; + /* Set up constants. */ + const uint16x8_t seven_u16 = vdupq_n_u16(7); + const uint8x8_t three_u8 = vdup_n_u8(3); + const uint16x8_t three_u16 = vdupq_n_u16(3); + + inrow = outrow = 0; + while (outrow < max_v_samp_factor) { + inptr0 = input_data[inrow - 1]; + inptr1 = input_data[inrow]; + inptr2 = input_data[inrow + 1]; + /* Suffixes 0 and 1 denote the upper and lower rows of output pixels, + * respectively. + */ + outptr0 = output_data[outrow++]; + outptr1 = output_data[outrow++]; + + /* First pixel component value in this row of the original image */ + int s0colsum0 = GETJSAMPLE(*inptr1) * 3 + GETJSAMPLE(*inptr0); + *outptr0 = (JSAMPLE)((s0colsum0 * 4 + 8) >> 4); + int s0colsum1 = GETJSAMPLE(*inptr1) * 3 + GETJSAMPLE(*inptr2); + *outptr1 = (JSAMPLE)((s0colsum1 * 4 + 8) >> 4); + + /* Step 1: Blend samples vertically in columns s0 and s1. + * Leave the divide by 4 until the end, when it can be done for both + * dimensions at once, right-shifting by 4. + */ + + /* Load and compute s0colsum0 and s0colsum1. */ + uint8x16_t s0A = vld1q_u8(inptr0); + uint8x16_t s0B = vld1q_u8(inptr1); + uint8x16_t s0C = vld1q_u8(inptr2); + /* Multiplication makes vectors twice as wide. '_l' and '_h' suffixes + * denote low half and high half respectively. + */ + uint16x8_t s0colsum0_l = vmlal_u8(vmovl_u8(vget_low_u8(s0A)), + vget_low_u8(s0B), three_u8); + uint16x8_t s0colsum0_h = vmlal_u8(vmovl_u8(vget_high_u8(s0A)), + vget_high_u8(s0B), three_u8); + uint16x8_t s0colsum1_l = vmlal_u8(vmovl_u8(vget_low_u8(s0C)), + vget_low_u8(s0B), three_u8); + uint16x8_t s0colsum1_h = vmlal_u8(vmovl_u8(vget_high_u8(s0C)), + vget_high_u8(s0B), three_u8); + /* Load and compute s1colsum0 and s1colsum1. */ + uint8x16_t s1A = vld1q_u8(inptr0 + 1); + uint8x16_t s1B = vld1q_u8(inptr1 + 1); + uint8x16_t s1C = vld1q_u8(inptr2 + 1); + uint16x8_t s1colsum0_l = vmlal_u8(vmovl_u8(vget_low_u8(s1A)), + vget_low_u8(s1B), three_u8); + uint16x8_t s1colsum0_h = vmlal_u8(vmovl_u8(vget_high_u8(s1A)), + vget_high_u8(s1B), three_u8); + uint16x8_t s1colsum1_l = vmlal_u8(vmovl_u8(vget_low_u8(s1C)), + vget_low_u8(s1B), three_u8); + uint16x8_t s1colsum1_h = vmlal_u8(vmovl_u8(vget_high_u8(s1C)), + vget_high_u8(s1B), three_u8); + + /* Step 2: Blend the already-blended columns. */ + + uint16x8_t output0_p1_l = vmlaq_u16(s1colsum0_l, s0colsum0_l, three_u16); + uint16x8_t output0_p1_h = vmlaq_u16(s1colsum0_h, s0colsum0_h, three_u16); + uint16x8_t output0_p2_l = vmlaq_u16(s0colsum0_l, s1colsum0_l, three_u16); + uint16x8_t output0_p2_h = vmlaq_u16(s0colsum0_h, s1colsum0_h, three_u16); + uint16x8_t output1_p1_l = vmlaq_u16(s1colsum1_l, s0colsum1_l, three_u16); + uint16x8_t output1_p1_h = vmlaq_u16(s1colsum1_h, s0colsum1_h, three_u16); + uint16x8_t output1_p2_l = vmlaq_u16(s0colsum1_l, s1colsum1_l, three_u16); + uint16x8_t output1_p2_h = vmlaq_u16(s0colsum1_h, s1colsum1_h, three_u16); + /* Add ordered dithering bias to odd pixel values. */ + output0_p1_l = vaddq_u16(output0_p1_l, seven_u16); + output0_p1_h = vaddq_u16(output0_p1_h, seven_u16); + output1_p1_l = vaddq_u16(output1_p1_l, seven_u16); + output1_p1_h = vaddq_u16(output1_p1_h, seven_u16); + /* Right-shift by 4 (divide by 16), narrow to 8-bit, and combine. */ + uint8x16x2_t output_pixels0 = { { + vcombine_u8(vshrn_n_u16(output0_p1_l, 4), vshrn_n_u16(output0_p1_h, 4)), + vcombine_u8(vrshrn_n_u16(output0_p2_l, 4), vrshrn_n_u16(output0_p2_h, 4)) + } }; + uint8x16x2_t output_pixels1 = { { + vcombine_u8(vshrn_n_u16(output1_p1_l, 4), vshrn_n_u16(output1_p1_h, 4)), + vcombine_u8(vrshrn_n_u16(output1_p2_l, 4), vrshrn_n_u16(output1_p2_h, 4)) + } }; + + /* Store pixel component values to memory. + * The minimum size of the output buffer for each row is 64 bytes => no + * need to worry about buffer overflow here. See "Creation of 2-D sample + * arrays" in jmemmgr.c for more details. + */ + vst2q_u8(outptr0 + 1, output_pixels0); + vst2q_u8(outptr1 + 1, output_pixels1); + + /* The first pixel of the image shifted our loads and stores by one byte. + * We have to re-align on a 32-byte boundary at some point before the end + * of the row (we do it now on the 32/33 pixel boundary) to stay within the + * bounds of the sample buffers without having to resort to a slow scalar + * tail case for the last (downsampled_width % 16) samples. See "Creation + * of 2-D sample arrays" in jmemmgr.c for more details. + */ + for (colctr = 16; colctr < downsampled_width; colctr += 16) { + /* Step 1: Blend samples vertically in columns s0 and s1. */ + + /* Load and compute s0colsum0 and s0colsum1. */ + s0A = vld1q_u8(inptr0 + colctr - 1); + s0B = vld1q_u8(inptr1 + colctr - 1); + s0C = vld1q_u8(inptr2 + colctr - 1); + s0colsum0_l = vmlal_u8(vmovl_u8(vget_low_u8(s0A)), vget_low_u8(s0B), + three_u8); + s0colsum0_h = vmlal_u8(vmovl_u8(vget_high_u8(s0A)), vget_high_u8(s0B), + three_u8); + s0colsum1_l = vmlal_u8(vmovl_u8(vget_low_u8(s0C)), vget_low_u8(s0B), + three_u8); + s0colsum1_h = vmlal_u8(vmovl_u8(vget_high_u8(s0C)), vget_high_u8(s0B), + three_u8); + /* Load and compute s1colsum0 and s1colsum1. */ + s1A = vld1q_u8(inptr0 + colctr); + s1B = vld1q_u8(inptr1 + colctr); + s1C = vld1q_u8(inptr2 + colctr); + s1colsum0_l = vmlal_u8(vmovl_u8(vget_low_u8(s1A)), vget_low_u8(s1B), + three_u8); + s1colsum0_h = vmlal_u8(vmovl_u8(vget_high_u8(s1A)), vget_high_u8(s1B), + three_u8); + s1colsum1_l = vmlal_u8(vmovl_u8(vget_low_u8(s1C)), vget_low_u8(s1B), + three_u8); + s1colsum1_h = vmlal_u8(vmovl_u8(vget_high_u8(s1C)), vget_high_u8(s1B), + three_u8); + + /* Step 2: Blend the already-blended columns. */ + + output0_p1_l = vmlaq_u16(s1colsum0_l, s0colsum0_l, three_u16); + output0_p1_h = vmlaq_u16(s1colsum0_h, s0colsum0_h, three_u16); + output0_p2_l = vmlaq_u16(s0colsum0_l, s1colsum0_l, three_u16); + output0_p2_h = vmlaq_u16(s0colsum0_h, s1colsum0_h, three_u16); + output1_p1_l = vmlaq_u16(s1colsum1_l, s0colsum1_l, three_u16); + output1_p1_h = vmlaq_u16(s1colsum1_h, s0colsum1_h, three_u16); + output1_p2_l = vmlaq_u16(s0colsum1_l, s1colsum1_l, three_u16); + output1_p2_h = vmlaq_u16(s0colsum1_h, s1colsum1_h, three_u16); + /* Add ordered dithering bias to odd pixel values. */ + output0_p1_l = vaddq_u16(output0_p1_l, seven_u16); + output0_p1_h = vaddq_u16(output0_p1_h, seven_u16); + output1_p1_l = vaddq_u16(output1_p1_l, seven_u16); + output1_p1_h = vaddq_u16(output1_p1_h, seven_u16); + /* Right-shift by 4 (divide by 16), narrow to 8-bit, and combine. */ + output_pixels0.val[0] = vcombine_u8(vshrn_n_u16(output0_p1_l, 4), + vshrn_n_u16(output0_p1_h, 4)); + output_pixels0.val[1] = vcombine_u8(vrshrn_n_u16(output0_p2_l, 4), + vrshrn_n_u16(output0_p2_h, 4)); + output_pixels1.val[0] = vcombine_u8(vshrn_n_u16(output1_p1_l, 4), + vshrn_n_u16(output1_p1_h, 4)); + output_pixels1.val[1] = vcombine_u8(vrshrn_n_u16(output1_p2_l, 4), + vrshrn_n_u16(output1_p2_h, 4)); + /* Store pixel component values to memory. */ + vst2q_u8(outptr0 + 2 * colctr - 1, output_pixels0); + vst2q_u8(outptr1 + 2 * colctr - 1, output_pixels1); + } + + /* Last pixel component value in this row of the original image */ + int s1colsum0 = GETJSAMPLE(inptr1[downsampled_width - 1]) * 3 + + GETJSAMPLE(inptr0[downsampled_width - 1]); + outptr0[2 * downsampled_width - 1] = (JSAMPLE)((s1colsum0 * 4 + 7) >> 4); + int s1colsum1 = GETJSAMPLE(inptr1[downsampled_width - 1]) * 3 + + GETJSAMPLE(inptr2[downsampled_width - 1]); + outptr1[2 * downsampled_width - 1] = (JSAMPLE)((s1colsum1 * 4 + 7) >> 4); + inrow++; + } +} + + +/* The diagram below shows a column of samples produced by h1v2 downsampling + * (or by losslessly rotating or transposing an h2v1-downsampled image.) + * + * +---------+ + * | p0 | + * sA | | + * | p1 | + * +---------+ + * | p2 | + * sB | | + * | p3 | + * +---------+ + * | p4 | + * sC | | + * | p5 | + * +---------+ + * + * Samples sA-sC were created by averaging the original pixel component values + * centered at positions p0-p5 above. To approximate those original pixel + * component values, we proportionally blend the adjacent samples in each + * column. + * + * An upsampled pixel component value is computed by blending the sample + * containing the pixel center with the nearest neighboring sample, in the + * ratio 3:1. For example: + * p1(upsampled) = 3/4 * sA + 1/4 * sB + * p2(upsampled) = 3/4 * sB + 1/4 * sA + * When computing the first and last pixel component values in the column, + * there is no adjacent sample to blend, so: + * p0(upsampled) = sA + * p5(upsampled) = sC + */ + +void jsimd_h1v2_fancy_upsample_neon(int max_v_samp_factor, + JDIMENSION downsampled_width, + JSAMPARRAY input_data, + JSAMPARRAY *output_data_ptr) +{ + JSAMPARRAY output_data = *output_data_ptr; + JSAMPROW inptr0, inptr1, inptr2, outptr0, outptr1; + int inrow, outrow; + unsigned colctr; + /* Set up constants. */ + const uint16x8_t one_u16 = vdupq_n_u16(1); + const uint8x8_t three_u8 = vdup_n_u8(3); + + inrow = outrow = 0; + while (outrow < max_v_samp_factor) { + inptr0 = input_data[inrow - 1]; + inptr1 = input_data[inrow]; + inptr2 = input_data[inrow + 1]; + /* Suffixes 0 and 1 denote the upper and lower rows of output pixels, + * respectively. + */ + outptr0 = output_data[outrow++]; + outptr1 = output_data[outrow++]; + inrow++; + + /* The size of the input and output buffers is always a multiple of 32 + * bytes => no need to worry about buffer overflow when reading/writing + * memory. See "Creation of 2-D sample arrays" in jmemmgr.c for more + * details. + */ + for (colctr = 0; colctr < downsampled_width; colctr += 16) { + /* Load samples. */ + uint8x16_t sA = vld1q_u8(inptr0 + colctr); + uint8x16_t sB = vld1q_u8(inptr1 + colctr); + uint8x16_t sC = vld1q_u8(inptr2 + colctr); + /* Blend samples vertically. */ + uint16x8_t colsum0_l = vmlal_u8(vmovl_u8(vget_low_u8(sA)), + vget_low_u8(sB), three_u8); + uint16x8_t colsum0_h = vmlal_u8(vmovl_u8(vget_high_u8(sA)), + vget_high_u8(sB), three_u8); + uint16x8_t colsum1_l = vmlal_u8(vmovl_u8(vget_low_u8(sC)), + vget_low_u8(sB), three_u8); + uint16x8_t colsum1_h = vmlal_u8(vmovl_u8(vget_high_u8(sC)), + vget_high_u8(sB), three_u8); + /* Add ordered dithering bias to pixel values in even output rows. */ + colsum0_l = vaddq_u16(colsum0_l, one_u16); + colsum0_h = vaddq_u16(colsum0_h, one_u16); + /* Right-shift by 2 (divide by 4), narrow to 8-bit, and combine. */ + uint8x16_t output_pixels0 = vcombine_u8(vshrn_n_u16(colsum0_l, 2), + vshrn_n_u16(colsum0_h, 2)); + uint8x16_t output_pixels1 = vcombine_u8(vrshrn_n_u16(colsum1_l, 2), + vrshrn_n_u16(colsum1_h, 2)); + /* Store pixel component values to memory. */ + vst1q_u8(outptr0 + colctr, output_pixels0); + vst1q_u8(outptr1 + colctr, output_pixels1); + } + } +} + + +/* The diagram below shows a row of samples produced by h2v1 downsampling. + * + * s0 s1 + * +---------+---------+ + * | | | + * | p0 p1 | p2 p3 | + * | | | + * +---------+---------+ + * + * Samples s0 and s1 were created by averaging the original pixel component + * values centered at positions p0-p3 above. To approximate those original + * pixel component values, we duplicate the samples horizontally: + * p0(upsampled) = p1(upsampled) = s0 + * p2(upsampled) = p3(upsampled) = s1 + */ + +void jsimd_h2v1_upsample_neon(int max_v_samp_factor, JDIMENSION output_width, + JSAMPARRAY input_data, + JSAMPARRAY *output_data_ptr) +{ + JSAMPARRAY output_data = *output_data_ptr; + JSAMPROW inptr, outptr; + int inrow; + unsigned colctr; + + for (inrow = 0; inrow < max_v_samp_factor; inrow++) { + inptr = input_data[inrow]; + outptr = output_data[inrow]; + for (colctr = 0; 2 * colctr < output_width; colctr += 16) { + uint8x16_t samples = vld1q_u8(inptr + colctr); + /* Duplicate the samples. The store operation below interleaves them so + * that adjacent pixel component values take on the same sample value, + * per above. + */ + uint8x16x2_t output_pixels = { { samples, samples } }; + /* Store pixel component values to memory. + * Due to the way sample buffers are allocated, we don't need to worry + * about tail cases when output_width is not a multiple of 32. See + * "Creation of 2-D sample arrays" in jmemmgr.c for details. + */ + vst2q_u8(outptr + 2 * colctr, output_pixels); + } + } +} + + +/* The diagram below shows an array of samples produced by h2v2 downsampling. + * + * s0 s1 + * +---------+---------+ + * | p0 p1 | p2 p3 | + * sA | | | + * | p4 p5 | p6 p7 | + * +---------+---------+ + * | p8 p9 | p10 p11| + * sB | | | + * | p12 p13| p14 p15| + * +---------+---------+ + * + * Samples s0A-s1B were created by averaging the original pixel component + * values centered at positions p0-p15 above. To approximate those original + * pixel component values, we duplicate the samples both horizontally and + * vertically: + * p0(upsampled) = p1(upsampled) = p4(upsampled) = p5(upsampled) = s0A + * p2(upsampled) = p3(upsampled) = p6(upsampled) = p7(upsampled) = s1A + * p8(upsampled) = p9(upsampled) = p12(upsampled) = p13(upsampled) = s0B + * p10(upsampled) = p11(upsampled) = p14(upsampled) = p15(upsampled) = s1B + */ + +void jsimd_h2v2_upsample_neon(int max_v_samp_factor, JDIMENSION output_width, + JSAMPARRAY input_data, + JSAMPARRAY *output_data_ptr) +{ + JSAMPARRAY output_data = *output_data_ptr; + JSAMPROW inptr, outptr0, outptr1; + int inrow, outrow; + unsigned colctr; + + for (inrow = 0, outrow = 0; outrow < max_v_samp_factor; inrow++) { + inptr = input_data[inrow]; + outptr0 = output_data[outrow++]; + outptr1 = output_data[outrow++]; + + for (colctr = 0; 2 * colctr < output_width; colctr += 16) { + uint8x16_t samples = vld1q_u8(inptr + colctr); + /* Duplicate the samples. The store operation below interleaves them so + * that adjacent pixel component values take on the same sample value, + * per above. + */ + uint8x16x2_t output_pixels = { { samples, samples } }; + /* Store pixel component values for both output rows to memory. + * Due to the way sample buffers are allocated, we don't need to worry + * about tail cases when output_width is not a multiple of 32. See + * "Creation of 2-D sample arrays" in jmemmgr.c for details. + */ + vst2q_u8(outptr0 + 2 * colctr, output_pixels); + vst2q_u8(outptr1 + 2 * colctr, output_pixels); + } + } +} |