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Diffstat (limited to 'media/libjpeg/simd/arm/jidctint-neon.c')
| -rw-r--r-- | media/libjpeg/simd/arm/jidctint-neon.c | 801 |
1 files changed, 801 insertions, 0 deletions
diff --git a/media/libjpeg/simd/arm/jidctint-neon.c b/media/libjpeg/simd/arm/jidctint-neon.c new file mode 100644 index 0000000000..d25112ef7f --- /dev/null +++ b/media/libjpeg/simd/arm/jidctint-neon.c @@ -0,0 +1,801 @@ +/* + * jidctint-neon.c - accurate integer IDCT (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 "align.h" +#include "neon-compat.h" + +#include <arm_neon.h> + + +#define CONST_BITS 13 +#define PASS1_BITS 2 + +#define DESCALE_P1 (CONST_BITS - PASS1_BITS) +#define DESCALE_P2 (CONST_BITS + PASS1_BITS + 3) + +/* The computation of the inverse DCT requires the use of constants known at + * compile time. Scaled integer constants are used to avoid floating-point + * arithmetic: + * 0.298631336 = 2446 * 2^-13 + * 0.390180644 = 3196 * 2^-13 + * 0.541196100 = 4433 * 2^-13 + * 0.765366865 = 6270 * 2^-13 + * 0.899976223 = 7373 * 2^-13 + * 1.175875602 = 9633 * 2^-13 + * 1.501321110 = 12299 * 2^-13 + * 1.847759065 = 15137 * 2^-13 + * 1.961570560 = 16069 * 2^-13 + * 2.053119869 = 16819 * 2^-13 + * 2.562915447 = 20995 * 2^-13 + * 3.072711026 = 25172 * 2^-13 + */ + +#define F_0_298 2446 +#define F_0_390 3196 +#define F_0_541 4433 +#define F_0_765 6270 +#define F_0_899 7373 +#define F_1_175 9633 +#define F_1_501 12299 +#define F_1_847 15137 +#define F_1_961 16069 +#define F_2_053 16819 +#define F_2_562 20995 +#define F_3_072 25172 + +#define F_1_175_MINUS_1_961 (F_1_175 - F_1_961) +#define F_1_175_MINUS_0_390 (F_1_175 - F_0_390) +#define F_0_541_MINUS_1_847 (F_0_541 - F_1_847) +#define F_3_072_MINUS_2_562 (F_3_072 - F_2_562) +#define F_0_298_MINUS_0_899 (F_0_298 - F_0_899) +#define F_1_501_MINUS_0_899 (F_1_501 - F_0_899) +#define F_2_053_MINUS_2_562 (F_2_053 - F_2_562) +#define F_0_541_PLUS_0_765 (F_0_541 + F_0_765) + + +ALIGN(16) static const int16_t jsimd_idct_islow_neon_consts[] = { + F_0_899, F_0_541, + F_2_562, F_0_298_MINUS_0_899, + F_1_501_MINUS_0_899, F_2_053_MINUS_2_562, + F_0_541_PLUS_0_765, F_1_175, + F_1_175_MINUS_0_390, F_0_541_MINUS_1_847, + F_3_072_MINUS_2_562, F_1_175_MINUS_1_961, + 0, 0, 0, 0 +}; + + +/* Forward declaration of regular and sparse IDCT helper functions */ + +static INLINE void jsimd_idct_islow_pass1_regular(int16x4_t row0, + int16x4_t row1, + int16x4_t row2, + int16x4_t row3, + int16x4_t row4, + int16x4_t row5, + int16x4_t row6, + int16x4_t row7, + int16x4_t quant_row0, + int16x4_t quant_row1, + int16x4_t quant_row2, + int16x4_t quant_row3, + int16x4_t quant_row4, + int16x4_t quant_row5, + int16x4_t quant_row6, + int16x4_t quant_row7, + int16_t *workspace_1, + int16_t *workspace_2); + +static INLINE void jsimd_idct_islow_pass1_sparse(int16x4_t row0, + int16x4_t row1, + int16x4_t row2, + int16x4_t row3, + int16x4_t quant_row0, + int16x4_t quant_row1, + int16x4_t quant_row2, + int16x4_t quant_row3, + int16_t *workspace_1, + int16_t *workspace_2); + +static INLINE void jsimd_idct_islow_pass2_regular(int16_t *workspace, + JSAMPARRAY output_buf, + JDIMENSION output_col, + unsigned buf_offset); + +static INLINE void jsimd_idct_islow_pass2_sparse(int16_t *workspace, + JSAMPARRAY output_buf, + JDIMENSION output_col, + unsigned buf_offset); + + +/* Perform dequantization and inverse DCT on one block of coefficients. For + * reference, the C implementation (jpeg_idct_slow()) can be found in + * jidctint.c. + * + * Optimization techniques used for fast data access: + * + * In each pass, the inverse DCT is computed for the left and right 4x8 halves + * of the DCT block. This avoids spilling due to register pressure, and the + * increased granularity allows for an optimized calculation depending on the + * values of the DCT coefficients. Between passes, intermediate data is stored + * in 4x8 workspace buffers. + * + * Transposing the 8x8 DCT block after each pass can be achieved by transposing + * each of the four 4x4 quadrants and swapping quadrants 1 and 2 (refer to the + * diagram below.) Swapping quadrants is cheap, since the second pass can just + * swap the workspace buffer pointers. + * + * +-------+-------+ +-------+-------+ + * | | | | | | + * | 0 | 1 | | 0 | 2 | + * | | | transpose | | | + * +-------+-------+ ------> +-------+-------+ + * | | | | | | + * | 2 | 3 | | 1 | 3 | + * | | | | | | + * +-------+-------+ +-------+-------+ + * + * Optimization techniques used to accelerate the inverse DCT calculation: + * + * In a DCT coefficient block, the coefficients are increasingly likely to be 0 + * as you move diagonally from top left to bottom right. If whole rows of + * coefficients are 0, then the inverse DCT calculation can be simplified. On + * the first pass of the inverse DCT, we test for three special cases before + * defaulting to a full "regular" inverse DCT: + * + * 1) Coefficients in rows 4-7 are all zero. In this case, we perform a + * "sparse" simplified inverse DCT on rows 0-3. + * 2) AC coefficients (rows 1-7) are all zero. In this case, the inverse DCT + * result is equal to the dequantized DC coefficients. + * 3) AC and DC coefficients are all zero. In this case, the inverse DCT + * result is all zero. For the left 4x8 half, this is handled identically + * to Case 2 above. For the right 4x8 half, we do no work and signal that + * the "sparse" algorithm is required for the second pass. + * + * In the second pass, only a single special case is tested: whether the AC and + * DC coefficients were all zero in the right 4x8 block during the first pass + * (refer to Case 3 above.) If this is the case, then a "sparse" variant of + * the second pass is performed for both the left and right halves of the DCT + * block. (The transposition after the first pass means that the right 4x8 + * block during the first pass becomes rows 4-7 during the second pass.) + */ + +void jsimd_idct_islow_neon(void *dct_table, JCOEFPTR coef_block, + JSAMPARRAY output_buf, JDIMENSION output_col) +{ + ISLOW_MULT_TYPE *quantptr = dct_table; + + int16_t workspace_l[8 * DCTSIZE / 2]; + int16_t workspace_r[8 * DCTSIZE / 2]; + + /* Compute IDCT first pass on left 4x8 coefficient block. */ + + /* Load DCT coefficients in left 4x8 block. */ + int16x4_t row0 = vld1_s16(coef_block + 0 * DCTSIZE); + int16x4_t row1 = vld1_s16(coef_block + 1 * DCTSIZE); + int16x4_t row2 = vld1_s16(coef_block + 2 * DCTSIZE); + int16x4_t row3 = vld1_s16(coef_block + 3 * DCTSIZE); + int16x4_t row4 = vld1_s16(coef_block + 4 * DCTSIZE); + int16x4_t row5 = vld1_s16(coef_block + 5 * DCTSIZE); + int16x4_t row6 = vld1_s16(coef_block + 6 * DCTSIZE); + int16x4_t row7 = vld1_s16(coef_block + 7 * DCTSIZE); + + /* Load quantization table for left 4x8 block. */ + int16x4_t quant_row0 = vld1_s16(quantptr + 0 * DCTSIZE); + int16x4_t quant_row1 = vld1_s16(quantptr + 1 * DCTSIZE); + int16x4_t quant_row2 = vld1_s16(quantptr + 2 * DCTSIZE); + int16x4_t quant_row3 = vld1_s16(quantptr + 3 * DCTSIZE); + int16x4_t quant_row4 = vld1_s16(quantptr + 4 * DCTSIZE); + int16x4_t quant_row5 = vld1_s16(quantptr + 5 * DCTSIZE); + int16x4_t quant_row6 = vld1_s16(quantptr + 6 * DCTSIZE); + int16x4_t quant_row7 = vld1_s16(quantptr + 7 * DCTSIZE); + + /* Construct bitmap to test if DCT coefficients in left 4x8 block are 0. */ + int16x4_t bitmap = vorr_s16(row7, row6); + bitmap = vorr_s16(bitmap, row5); + bitmap = vorr_s16(bitmap, row4); + int64_t bitmap_rows_4567 = vget_lane_s64(vreinterpret_s64_s16(bitmap), 0); + + if (bitmap_rows_4567 == 0) { + bitmap = vorr_s16(bitmap, row3); + bitmap = vorr_s16(bitmap, row2); + bitmap = vorr_s16(bitmap, row1); + int64_t left_ac_bitmap = vget_lane_s64(vreinterpret_s64_s16(bitmap), 0); + + if (left_ac_bitmap == 0) { + int16x4_t dcval = vshl_n_s16(vmul_s16(row0, quant_row0), PASS1_BITS); + int16x4x4_t quadrant = { { dcval, dcval, dcval, dcval } }; + /* Store 4x4 blocks to workspace, transposing in the process. */ + vst4_s16(workspace_l, quadrant); + vst4_s16(workspace_r, quadrant); + } else { + jsimd_idct_islow_pass1_sparse(row0, row1, row2, row3, quant_row0, + quant_row1, quant_row2, quant_row3, + workspace_l, workspace_r); + } + } else { + jsimd_idct_islow_pass1_regular(row0, row1, row2, row3, row4, row5, + row6, row7, quant_row0, quant_row1, + quant_row2, quant_row3, quant_row4, + quant_row5, quant_row6, quant_row7, + workspace_l, workspace_r); + } + + /* Compute IDCT first pass on right 4x8 coefficient block. */ + + /* Load DCT coefficients in right 4x8 block. */ + row0 = vld1_s16(coef_block + 0 * DCTSIZE + 4); + row1 = vld1_s16(coef_block + 1 * DCTSIZE + 4); + row2 = vld1_s16(coef_block + 2 * DCTSIZE + 4); + row3 = vld1_s16(coef_block + 3 * DCTSIZE + 4); + row4 = vld1_s16(coef_block + 4 * DCTSIZE + 4); + row5 = vld1_s16(coef_block + 5 * DCTSIZE + 4); + row6 = vld1_s16(coef_block + 6 * DCTSIZE + 4); + row7 = vld1_s16(coef_block + 7 * DCTSIZE + 4); + + /* Load quantization table for right 4x8 block. */ + quant_row0 = vld1_s16(quantptr + 0 * DCTSIZE + 4); + quant_row1 = vld1_s16(quantptr + 1 * DCTSIZE + 4); + quant_row2 = vld1_s16(quantptr + 2 * DCTSIZE + 4); + quant_row3 = vld1_s16(quantptr + 3 * DCTSIZE + 4); + quant_row4 = vld1_s16(quantptr + 4 * DCTSIZE + 4); + quant_row5 = vld1_s16(quantptr + 5 * DCTSIZE + 4); + quant_row6 = vld1_s16(quantptr + 6 * DCTSIZE + 4); + quant_row7 = vld1_s16(quantptr + 7 * DCTSIZE + 4); + + /* Construct bitmap to test if DCT coefficients in right 4x8 block are 0. */ + bitmap = vorr_s16(row7, row6); + bitmap = vorr_s16(bitmap, row5); + bitmap = vorr_s16(bitmap, row4); + bitmap_rows_4567 = vget_lane_s64(vreinterpret_s64_s16(bitmap), 0); + bitmap = vorr_s16(bitmap, row3); + bitmap = vorr_s16(bitmap, row2); + bitmap = vorr_s16(bitmap, row1); + int64_t right_ac_bitmap = vget_lane_s64(vreinterpret_s64_s16(bitmap), 0); + + /* If this remains non-zero, a "regular" second pass will be performed. */ + int64_t right_ac_dc_bitmap = 1; + + if (right_ac_bitmap == 0) { + bitmap = vorr_s16(bitmap, row0); + right_ac_dc_bitmap = vget_lane_s64(vreinterpret_s64_s16(bitmap), 0); + + if (right_ac_dc_bitmap != 0) { + int16x4_t dcval = vshl_n_s16(vmul_s16(row0, quant_row0), PASS1_BITS); + int16x4x4_t quadrant = { { dcval, dcval, dcval, dcval } }; + /* Store 4x4 blocks to workspace, transposing in the process. */ + vst4_s16(workspace_l + 4 * DCTSIZE / 2, quadrant); + vst4_s16(workspace_r + 4 * DCTSIZE / 2, quadrant); + } + } else { + if (bitmap_rows_4567 == 0) { + jsimd_idct_islow_pass1_sparse(row0, row1, row2, row3, quant_row0, + quant_row1, quant_row2, quant_row3, + workspace_l + 4 * DCTSIZE / 2, + workspace_r + 4 * DCTSIZE / 2); + } else { + jsimd_idct_islow_pass1_regular(row0, row1, row2, row3, row4, row5, + row6, row7, quant_row0, quant_row1, + quant_row2, quant_row3, quant_row4, + quant_row5, quant_row6, quant_row7, + workspace_l + 4 * DCTSIZE / 2, + workspace_r + 4 * DCTSIZE / 2); + } + } + + /* Second pass: compute IDCT on rows in workspace. */ + + /* If all coefficients in right 4x8 block are 0, use "sparse" second pass. */ + if (right_ac_dc_bitmap == 0) { + jsimd_idct_islow_pass2_sparse(workspace_l, output_buf, output_col, 0); + jsimd_idct_islow_pass2_sparse(workspace_r, output_buf, output_col, 4); + } else { + jsimd_idct_islow_pass2_regular(workspace_l, output_buf, output_col, 0); + jsimd_idct_islow_pass2_regular(workspace_r, output_buf, output_col, 4); + } +} + + +/* Perform dequantization and the first pass of the accurate inverse DCT on a + * 4x8 block of coefficients. (To process the full 8x8 DCT block, this + * function-- or some other optimized variant-- needs to be called for both the + * left and right 4x8 blocks.) + * + * This "regular" version assumes that no optimization can be made to the IDCT + * calculation, since no useful set of AC coefficients is all 0. + * + * The original C implementation of the accurate IDCT (jpeg_idct_slow()) can be + * found in jidctint.c. Algorithmic changes made here are documented inline. + */ + +static INLINE void jsimd_idct_islow_pass1_regular(int16x4_t row0, + int16x4_t row1, + int16x4_t row2, + int16x4_t row3, + int16x4_t row4, + int16x4_t row5, + int16x4_t row6, + int16x4_t row7, + int16x4_t quant_row0, + int16x4_t quant_row1, + int16x4_t quant_row2, + int16x4_t quant_row3, + int16x4_t quant_row4, + int16x4_t quant_row5, + int16x4_t quant_row6, + int16x4_t quant_row7, + int16_t *workspace_1, + int16_t *workspace_2) +{ + /* Load constants for IDCT computation. */ +#ifdef HAVE_VLD1_S16_X3 + const int16x4x3_t consts = vld1_s16_x3(jsimd_idct_islow_neon_consts); +#else + const int16x4_t consts1 = vld1_s16(jsimd_idct_islow_neon_consts); + const int16x4_t consts2 = vld1_s16(jsimd_idct_islow_neon_consts + 4); + const int16x4_t consts3 = vld1_s16(jsimd_idct_islow_neon_consts + 8); + const int16x4x3_t consts = { { consts1, consts2, consts3 } }; +#endif + + /* Even part */ + int16x4_t z2_s16 = vmul_s16(row2, quant_row2); + int16x4_t z3_s16 = vmul_s16(row6, quant_row6); + + int32x4_t tmp2 = vmull_lane_s16(z2_s16, consts.val[0], 1); + int32x4_t tmp3 = vmull_lane_s16(z2_s16, consts.val[1], 2); + tmp2 = vmlal_lane_s16(tmp2, z3_s16, consts.val[2], 1); + tmp3 = vmlal_lane_s16(tmp3, z3_s16, consts.val[0], 1); + + z2_s16 = vmul_s16(row0, quant_row0); + z3_s16 = vmul_s16(row4, quant_row4); + + int32x4_t tmp0 = vshll_n_s16(vadd_s16(z2_s16, z3_s16), CONST_BITS); + int32x4_t tmp1 = vshll_n_s16(vsub_s16(z2_s16, z3_s16), CONST_BITS); + + int32x4_t tmp10 = vaddq_s32(tmp0, tmp3); + int32x4_t tmp13 = vsubq_s32(tmp0, tmp3); + int32x4_t tmp11 = vaddq_s32(tmp1, tmp2); + int32x4_t tmp12 = vsubq_s32(tmp1, tmp2); + + /* Odd part */ + int16x4_t tmp0_s16 = vmul_s16(row7, quant_row7); + int16x4_t tmp1_s16 = vmul_s16(row5, quant_row5); + int16x4_t tmp2_s16 = vmul_s16(row3, quant_row3); + int16x4_t tmp3_s16 = vmul_s16(row1, quant_row1); + + z3_s16 = vadd_s16(tmp0_s16, tmp2_s16); + int16x4_t z4_s16 = vadd_s16(tmp1_s16, tmp3_s16); + + /* Implementation as per jpeg_idct_islow() in jidctint.c: + * z5 = (z3 + z4) * 1.175875602; + * z3 = z3 * -1.961570560; z4 = z4 * -0.390180644; + * z3 += z5; z4 += z5; + * + * This implementation: + * z3 = z3 * (1.175875602 - 1.961570560) + z4 * 1.175875602; + * z4 = z3 * 1.175875602 + z4 * (1.175875602 - 0.390180644); + */ + + int32x4_t z3 = vmull_lane_s16(z3_s16, consts.val[2], 3); + int32x4_t z4 = vmull_lane_s16(z3_s16, consts.val[1], 3); + z3 = vmlal_lane_s16(z3, z4_s16, consts.val[1], 3); + z4 = vmlal_lane_s16(z4, z4_s16, consts.val[2], 0); + + /* Implementation as per jpeg_idct_islow() in jidctint.c: + * z1 = tmp0 + tmp3; z2 = tmp1 + tmp2; + * tmp0 = tmp0 * 0.298631336; tmp1 = tmp1 * 2.053119869; + * tmp2 = tmp2 * 3.072711026; tmp3 = tmp3 * 1.501321110; + * z1 = z1 * -0.899976223; z2 = z2 * -2.562915447; + * tmp0 += z1 + z3; tmp1 += z2 + z4; + * tmp2 += z2 + z3; tmp3 += z1 + z4; + * + * This implementation: + * tmp0 = tmp0 * (0.298631336 - 0.899976223) + tmp3 * -0.899976223; + * tmp1 = tmp1 * (2.053119869 - 2.562915447) + tmp2 * -2.562915447; + * tmp2 = tmp1 * -2.562915447 + tmp2 * (3.072711026 - 2.562915447); + * tmp3 = tmp0 * -0.899976223 + tmp3 * (1.501321110 - 0.899976223); + * tmp0 += z3; tmp1 += z4; + * tmp2 += z3; tmp3 += z4; + */ + + tmp0 = vmull_lane_s16(tmp0_s16, consts.val[0], 3); + tmp1 = vmull_lane_s16(tmp1_s16, consts.val[1], 1); + tmp2 = vmull_lane_s16(tmp2_s16, consts.val[2], 2); + tmp3 = vmull_lane_s16(tmp3_s16, consts.val[1], 0); + + tmp0 = vmlsl_lane_s16(tmp0, tmp3_s16, consts.val[0], 0); + tmp1 = vmlsl_lane_s16(tmp1, tmp2_s16, consts.val[0], 2); + tmp2 = vmlsl_lane_s16(tmp2, tmp1_s16, consts.val[0], 2); + tmp3 = vmlsl_lane_s16(tmp3, tmp0_s16, consts.val[0], 0); + + tmp0 = vaddq_s32(tmp0, z3); + tmp1 = vaddq_s32(tmp1, z4); + tmp2 = vaddq_s32(tmp2, z3); + tmp3 = vaddq_s32(tmp3, z4); + + /* Final output stage: descale and narrow to 16-bit. */ + int16x4x4_t rows_0123 = { { + vrshrn_n_s32(vaddq_s32(tmp10, tmp3), DESCALE_P1), + vrshrn_n_s32(vaddq_s32(tmp11, tmp2), DESCALE_P1), + vrshrn_n_s32(vaddq_s32(tmp12, tmp1), DESCALE_P1), + vrshrn_n_s32(vaddq_s32(tmp13, tmp0), DESCALE_P1) + } }; + int16x4x4_t rows_4567 = { { + vrshrn_n_s32(vsubq_s32(tmp13, tmp0), DESCALE_P1), + vrshrn_n_s32(vsubq_s32(tmp12, tmp1), DESCALE_P1), + vrshrn_n_s32(vsubq_s32(tmp11, tmp2), DESCALE_P1), + vrshrn_n_s32(vsubq_s32(tmp10, tmp3), DESCALE_P1) + } }; + + /* Store 4x4 blocks to the intermediate workspace, ready for the second pass. + * (VST4 transposes the blocks. We need to operate on rows in the next + * pass.) + */ + vst4_s16(workspace_1, rows_0123); + vst4_s16(workspace_2, rows_4567); +} + + +/* Perform dequantization and the first pass of the accurate inverse DCT on a + * 4x8 block of coefficients. + * + * This "sparse" version assumes that the AC coefficients in rows 4-7 are all + * 0. This simplifies the IDCT calculation, accelerating overall performance. + */ + +static INLINE void jsimd_idct_islow_pass1_sparse(int16x4_t row0, + int16x4_t row1, + int16x4_t row2, + int16x4_t row3, + int16x4_t quant_row0, + int16x4_t quant_row1, + int16x4_t quant_row2, + int16x4_t quant_row3, + int16_t *workspace_1, + int16_t *workspace_2) +{ + /* Load constants for IDCT computation. */ +#ifdef HAVE_VLD1_S16_X3 + const int16x4x3_t consts = vld1_s16_x3(jsimd_idct_islow_neon_consts); +#else + const int16x4_t consts1 = vld1_s16(jsimd_idct_islow_neon_consts); + const int16x4_t consts2 = vld1_s16(jsimd_idct_islow_neon_consts + 4); + const int16x4_t consts3 = vld1_s16(jsimd_idct_islow_neon_consts + 8); + const int16x4x3_t consts = { { consts1, consts2, consts3 } }; +#endif + + /* Even part (z3 is all 0) */ + int16x4_t z2_s16 = vmul_s16(row2, quant_row2); + + int32x4_t tmp2 = vmull_lane_s16(z2_s16, consts.val[0], 1); + int32x4_t tmp3 = vmull_lane_s16(z2_s16, consts.val[1], 2); + + z2_s16 = vmul_s16(row0, quant_row0); + int32x4_t tmp0 = vshll_n_s16(z2_s16, CONST_BITS); + int32x4_t tmp1 = vshll_n_s16(z2_s16, CONST_BITS); + + int32x4_t tmp10 = vaddq_s32(tmp0, tmp3); + int32x4_t tmp13 = vsubq_s32(tmp0, tmp3); + int32x4_t tmp11 = vaddq_s32(tmp1, tmp2); + int32x4_t tmp12 = vsubq_s32(tmp1, tmp2); + + /* Odd part (tmp0 and tmp1 are both all 0) */ + int16x4_t tmp2_s16 = vmul_s16(row3, quant_row3); + int16x4_t tmp3_s16 = vmul_s16(row1, quant_row1); + + int16x4_t z3_s16 = tmp2_s16; + int16x4_t z4_s16 = tmp3_s16; + + int32x4_t z3 = vmull_lane_s16(z3_s16, consts.val[2], 3); + int32x4_t z4 = vmull_lane_s16(z3_s16, consts.val[1], 3); + z3 = vmlal_lane_s16(z3, z4_s16, consts.val[1], 3); + z4 = vmlal_lane_s16(z4, z4_s16, consts.val[2], 0); + + tmp0 = vmlsl_lane_s16(z3, tmp3_s16, consts.val[0], 0); + tmp1 = vmlsl_lane_s16(z4, tmp2_s16, consts.val[0], 2); + tmp2 = vmlal_lane_s16(z3, tmp2_s16, consts.val[2], 2); + tmp3 = vmlal_lane_s16(z4, tmp3_s16, consts.val[1], 0); + + /* Final output stage: descale and narrow to 16-bit. */ + int16x4x4_t rows_0123 = { { + vrshrn_n_s32(vaddq_s32(tmp10, tmp3), DESCALE_P1), + vrshrn_n_s32(vaddq_s32(tmp11, tmp2), DESCALE_P1), + vrshrn_n_s32(vaddq_s32(tmp12, tmp1), DESCALE_P1), + vrshrn_n_s32(vaddq_s32(tmp13, tmp0), DESCALE_P1) + } }; + int16x4x4_t rows_4567 = { { + vrshrn_n_s32(vsubq_s32(tmp13, tmp0), DESCALE_P1), + vrshrn_n_s32(vsubq_s32(tmp12, tmp1), DESCALE_P1), + vrshrn_n_s32(vsubq_s32(tmp11, tmp2), DESCALE_P1), + vrshrn_n_s32(vsubq_s32(tmp10, tmp3), DESCALE_P1) + } }; + + /* Store 4x4 blocks to the intermediate workspace, ready for the second pass. + * (VST4 transposes the blocks. We need to operate on rows in the next + * pass.) + */ + vst4_s16(workspace_1, rows_0123); + vst4_s16(workspace_2, rows_4567); +} + + +/* Perform the second pass of the accurate inverse DCT on a 4x8 block of + * coefficients. (To process the full 8x8 DCT block, this function-- or some + * other optimized variant-- needs to be called for both the right and left 4x8 + * blocks.) + * + * This "regular" version assumes that no optimization can be made to the IDCT + * calculation, since no useful set of coefficient values are all 0 after the + * first pass. + * + * Again, the original C implementation of the accurate IDCT (jpeg_idct_slow()) + * can be found in jidctint.c. Algorithmic changes made here are documented + * inline. + */ + +static INLINE void jsimd_idct_islow_pass2_regular(int16_t *workspace, + JSAMPARRAY output_buf, + JDIMENSION output_col, + unsigned buf_offset) +{ + /* Load constants for IDCT computation. */ +#ifdef HAVE_VLD1_S16_X3 + const int16x4x3_t consts = vld1_s16_x3(jsimd_idct_islow_neon_consts); +#else + const int16x4_t consts1 = vld1_s16(jsimd_idct_islow_neon_consts); + const int16x4_t consts2 = vld1_s16(jsimd_idct_islow_neon_consts + 4); + const int16x4_t consts3 = vld1_s16(jsimd_idct_islow_neon_consts + 8); + const int16x4x3_t consts = { { consts1, consts2, consts3 } }; +#endif + + /* Even part */ + int16x4_t z2_s16 = vld1_s16(workspace + 2 * DCTSIZE / 2); + int16x4_t z3_s16 = vld1_s16(workspace + 6 * DCTSIZE / 2); + + int32x4_t tmp2 = vmull_lane_s16(z2_s16, consts.val[0], 1); + int32x4_t tmp3 = vmull_lane_s16(z2_s16, consts.val[1], 2); + tmp2 = vmlal_lane_s16(tmp2, z3_s16, consts.val[2], 1); + tmp3 = vmlal_lane_s16(tmp3, z3_s16, consts.val[0], 1); + + z2_s16 = vld1_s16(workspace + 0 * DCTSIZE / 2); + z3_s16 = vld1_s16(workspace + 4 * DCTSIZE / 2); + + int32x4_t tmp0 = vshll_n_s16(vadd_s16(z2_s16, z3_s16), CONST_BITS); + int32x4_t tmp1 = vshll_n_s16(vsub_s16(z2_s16, z3_s16), CONST_BITS); + + int32x4_t tmp10 = vaddq_s32(tmp0, tmp3); + int32x4_t tmp13 = vsubq_s32(tmp0, tmp3); + int32x4_t tmp11 = vaddq_s32(tmp1, tmp2); + int32x4_t tmp12 = vsubq_s32(tmp1, tmp2); + + /* Odd part */ + int16x4_t tmp0_s16 = vld1_s16(workspace + 7 * DCTSIZE / 2); + int16x4_t tmp1_s16 = vld1_s16(workspace + 5 * DCTSIZE / 2); + int16x4_t tmp2_s16 = vld1_s16(workspace + 3 * DCTSIZE / 2); + int16x4_t tmp3_s16 = vld1_s16(workspace + 1 * DCTSIZE / 2); + + z3_s16 = vadd_s16(tmp0_s16, tmp2_s16); + int16x4_t z4_s16 = vadd_s16(tmp1_s16, tmp3_s16); + + /* Implementation as per jpeg_idct_islow() in jidctint.c: + * z5 = (z3 + z4) * 1.175875602; + * z3 = z3 * -1.961570560; z4 = z4 * -0.390180644; + * z3 += z5; z4 += z5; + * + * This implementation: + * z3 = z3 * (1.175875602 - 1.961570560) + z4 * 1.175875602; + * z4 = z3 * 1.175875602 + z4 * (1.175875602 - 0.390180644); + */ + + int32x4_t z3 = vmull_lane_s16(z3_s16, consts.val[2], 3); + int32x4_t z4 = vmull_lane_s16(z3_s16, consts.val[1], 3); + z3 = vmlal_lane_s16(z3, z4_s16, consts.val[1], 3); + z4 = vmlal_lane_s16(z4, z4_s16, consts.val[2], 0); + + /* Implementation as per jpeg_idct_islow() in jidctint.c: + * z1 = tmp0 + tmp3; z2 = tmp1 + tmp2; + * tmp0 = tmp0 * 0.298631336; tmp1 = tmp1 * 2.053119869; + * tmp2 = tmp2 * 3.072711026; tmp3 = tmp3 * 1.501321110; + * z1 = z1 * -0.899976223; z2 = z2 * -2.562915447; + * tmp0 += z1 + z3; tmp1 += z2 + z4; + * tmp2 += z2 + z3; tmp3 += z1 + z4; + * + * This implementation: + * tmp0 = tmp0 * (0.298631336 - 0.899976223) + tmp3 * -0.899976223; + * tmp1 = tmp1 * (2.053119869 - 2.562915447) + tmp2 * -2.562915447; + * tmp2 = tmp1 * -2.562915447 + tmp2 * (3.072711026 - 2.562915447); + * tmp3 = tmp0 * -0.899976223 + tmp3 * (1.501321110 - 0.899976223); + * tmp0 += z3; tmp1 += z4; + * tmp2 += z3; tmp3 += z4; + */ + + tmp0 = vmull_lane_s16(tmp0_s16, consts.val[0], 3); + tmp1 = vmull_lane_s16(tmp1_s16, consts.val[1], 1); + tmp2 = vmull_lane_s16(tmp2_s16, consts.val[2], 2); + tmp3 = vmull_lane_s16(tmp3_s16, consts.val[1], 0); + + tmp0 = vmlsl_lane_s16(tmp0, tmp3_s16, consts.val[0], 0); + tmp1 = vmlsl_lane_s16(tmp1, tmp2_s16, consts.val[0], 2); + tmp2 = vmlsl_lane_s16(tmp2, tmp1_s16, consts.val[0], 2); + tmp3 = vmlsl_lane_s16(tmp3, tmp0_s16, consts.val[0], 0); + + tmp0 = vaddq_s32(tmp0, z3); + tmp1 = vaddq_s32(tmp1, z4); + tmp2 = vaddq_s32(tmp2, z3); + tmp3 = vaddq_s32(tmp3, z4); + + /* Final output stage: descale and narrow to 16-bit. */ + int16x8_t cols_02_s16 = vcombine_s16(vaddhn_s32(tmp10, tmp3), + vaddhn_s32(tmp12, tmp1)); + int16x8_t cols_13_s16 = vcombine_s16(vaddhn_s32(tmp11, tmp2), + vaddhn_s32(tmp13, tmp0)); + int16x8_t cols_46_s16 = vcombine_s16(vsubhn_s32(tmp13, tmp0), + vsubhn_s32(tmp11, tmp2)); + int16x8_t cols_57_s16 = vcombine_s16(vsubhn_s32(tmp12, tmp1), + vsubhn_s32(tmp10, tmp3)); + /* Descale and narrow to 8-bit. */ + int8x8_t cols_02_s8 = vqrshrn_n_s16(cols_02_s16, DESCALE_P2 - 16); + int8x8_t cols_13_s8 = vqrshrn_n_s16(cols_13_s16, DESCALE_P2 - 16); + int8x8_t cols_46_s8 = vqrshrn_n_s16(cols_46_s16, DESCALE_P2 - 16); + int8x8_t cols_57_s8 = vqrshrn_n_s16(cols_57_s16, DESCALE_P2 - 16); + /* Clamp to range [0-255]. */ + uint8x8_t cols_02_u8 = vadd_u8(vreinterpret_u8_s8(cols_02_s8), + vdup_n_u8(CENTERJSAMPLE)); + uint8x8_t cols_13_u8 = vadd_u8(vreinterpret_u8_s8(cols_13_s8), + vdup_n_u8(CENTERJSAMPLE)); + uint8x8_t cols_46_u8 = vadd_u8(vreinterpret_u8_s8(cols_46_s8), + vdup_n_u8(CENTERJSAMPLE)); + uint8x8_t cols_57_u8 = vadd_u8(vreinterpret_u8_s8(cols_57_s8), + vdup_n_u8(CENTERJSAMPLE)); + + /* Transpose 4x8 block and store to memory. (Zipping adjacent columns + * together allows us to store 16-bit elements.) + */ + uint8x8x2_t cols_01_23 = vzip_u8(cols_02_u8, cols_13_u8); + uint8x8x2_t cols_45_67 = vzip_u8(cols_46_u8, cols_57_u8); + uint16x4x4_t cols_01_23_45_67 = { { + vreinterpret_u16_u8(cols_01_23.val[0]), + vreinterpret_u16_u8(cols_01_23.val[1]), + vreinterpret_u16_u8(cols_45_67.val[0]), + vreinterpret_u16_u8(cols_45_67.val[1]) + } }; + + JSAMPROW outptr0 = output_buf[buf_offset + 0] + output_col; + JSAMPROW outptr1 = output_buf[buf_offset + 1] + output_col; + JSAMPROW outptr2 = output_buf[buf_offset + 2] + output_col; + JSAMPROW outptr3 = output_buf[buf_offset + 3] + output_col; + /* VST4 of 16-bit elements completes the transpose. */ + vst4_lane_u16((uint16_t *)outptr0, cols_01_23_45_67, 0); + vst4_lane_u16((uint16_t *)outptr1, cols_01_23_45_67, 1); + vst4_lane_u16((uint16_t *)outptr2, cols_01_23_45_67, 2); + vst4_lane_u16((uint16_t *)outptr3, cols_01_23_45_67, 3); +} + + +/* Performs the second pass of the accurate inverse DCT on a 4x8 block + * of coefficients. + * + * This "sparse" version assumes that the coefficient values (after the first + * pass) in rows 4-7 are all 0. This simplifies the IDCT calculation, + * accelerating overall performance. + */ + +static INLINE void jsimd_idct_islow_pass2_sparse(int16_t *workspace, + JSAMPARRAY output_buf, + JDIMENSION output_col, + unsigned buf_offset) +{ + /* Load constants for IDCT computation. */ +#ifdef HAVE_VLD1_S16_X3 + const int16x4x3_t consts = vld1_s16_x3(jsimd_idct_islow_neon_consts); +#else + const int16x4_t consts1 = vld1_s16(jsimd_idct_islow_neon_consts); + const int16x4_t consts2 = vld1_s16(jsimd_idct_islow_neon_consts + 4); + const int16x4_t consts3 = vld1_s16(jsimd_idct_islow_neon_consts + 8); + const int16x4x3_t consts = { { consts1, consts2, consts3 } }; +#endif + + /* Even part (z3 is all 0) */ + int16x4_t z2_s16 = vld1_s16(workspace + 2 * DCTSIZE / 2); + + int32x4_t tmp2 = vmull_lane_s16(z2_s16, consts.val[0], 1); + int32x4_t tmp3 = vmull_lane_s16(z2_s16, consts.val[1], 2); + + z2_s16 = vld1_s16(workspace + 0 * DCTSIZE / 2); + int32x4_t tmp0 = vshll_n_s16(z2_s16, CONST_BITS); + int32x4_t tmp1 = vshll_n_s16(z2_s16, CONST_BITS); + + int32x4_t tmp10 = vaddq_s32(tmp0, tmp3); + int32x4_t tmp13 = vsubq_s32(tmp0, tmp3); + int32x4_t tmp11 = vaddq_s32(tmp1, tmp2); + int32x4_t tmp12 = vsubq_s32(tmp1, tmp2); + + /* Odd part (tmp0 and tmp1 are both all 0) */ + int16x4_t tmp2_s16 = vld1_s16(workspace + 3 * DCTSIZE / 2); + int16x4_t tmp3_s16 = vld1_s16(workspace + 1 * DCTSIZE / 2); + + int16x4_t z3_s16 = tmp2_s16; + int16x4_t z4_s16 = tmp3_s16; + + int32x4_t z3 = vmull_lane_s16(z3_s16, consts.val[2], 3); + z3 = vmlal_lane_s16(z3, z4_s16, consts.val[1], 3); + int32x4_t z4 = vmull_lane_s16(z3_s16, consts.val[1], 3); + z4 = vmlal_lane_s16(z4, z4_s16, consts.val[2], 0); + + tmp0 = vmlsl_lane_s16(z3, tmp3_s16, consts.val[0], 0); + tmp1 = vmlsl_lane_s16(z4, tmp2_s16, consts.val[0], 2); + tmp2 = vmlal_lane_s16(z3, tmp2_s16, consts.val[2], 2); + tmp3 = vmlal_lane_s16(z4, tmp3_s16, consts.val[1], 0); + + /* Final output stage: descale and narrow to 16-bit. */ + int16x8_t cols_02_s16 = vcombine_s16(vaddhn_s32(tmp10, tmp3), + vaddhn_s32(tmp12, tmp1)); + int16x8_t cols_13_s16 = vcombine_s16(vaddhn_s32(tmp11, tmp2), + vaddhn_s32(tmp13, tmp0)); + int16x8_t cols_46_s16 = vcombine_s16(vsubhn_s32(tmp13, tmp0), + vsubhn_s32(tmp11, tmp2)); + int16x8_t cols_57_s16 = vcombine_s16(vsubhn_s32(tmp12, tmp1), + vsubhn_s32(tmp10, tmp3)); + /* Descale and narrow to 8-bit. */ + int8x8_t cols_02_s8 = vqrshrn_n_s16(cols_02_s16, DESCALE_P2 - 16); + int8x8_t cols_13_s8 = vqrshrn_n_s16(cols_13_s16, DESCALE_P2 - 16); + int8x8_t cols_46_s8 = vqrshrn_n_s16(cols_46_s16, DESCALE_P2 - 16); + int8x8_t cols_57_s8 = vqrshrn_n_s16(cols_57_s16, DESCALE_P2 - 16); + /* Clamp to range [0-255]. */ + uint8x8_t cols_02_u8 = vadd_u8(vreinterpret_u8_s8(cols_02_s8), + vdup_n_u8(CENTERJSAMPLE)); + uint8x8_t cols_13_u8 = vadd_u8(vreinterpret_u8_s8(cols_13_s8), + vdup_n_u8(CENTERJSAMPLE)); + uint8x8_t cols_46_u8 = vadd_u8(vreinterpret_u8_s8(cols_46_s8), + vdup_n_u8(CENTERJSAMPLE)); + uint8x8_t cols_57_u8 = vadd_u8(vreinterpret_u8_s8(cols_57_s8), + vdup_n_u8(CENTERJSAMPLE)); + + /* Transpose 4x8 block and store to memory. (Zipping adjacent columns + * together allows us to store 16-bit elements.) + */ + uint8x8x2_t cols_01_23 = vzip_u8(cols_02_u8, cols_13_u8); + uint8x8x2_t cols_45_67 = vzip_u8(cols_46_u8, cols_57_u8); + uint16x4x4_t cols_01_23_45_67 = { { + vreinterpret_u16_u8(cols_01_23.val[0]), + vreinterpret_u16_u8(cols_01_23.val[1]), + vreinterpret_u16_u8(cols_45_67.val[0]), + vreinterpret_u16_u8(cols_45_67.val[1]) + } }; + + JSAMPROW outptr0 = output_buf[buf_offset + 0] + output_col; + JSAMPROW outptr1 = output_buf[buf_offset + 1] + output_col; + JSAMPROW outptr2 = output_buf[buf_offset + 2] + output_col; + JSAMPROW outptr3 = output_buf[buf_offset + 3] + output_col; + /* VST4 of 16-bit elements completes the transpose. */ + vst4_lane_u16((uint16_t *)outptr0, cols_01_23_45_67, 0); + vst4_lane_u16((uint16_t *)outptr1, cols_01_23_45_67, 1); + vst4_lane_u16((uint16_t *)outptr2, cols_01_23_45_67, 2); + vst4_lane_u16((uint16_t *)outptr3, cols_01_23_45_67, 3); +} |