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diff --git a/media/libjpeg/simd/arm/jidctint-neon.c b/media/libjpeg/simd/arm/jidctint-neon.c
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+/*
+ * 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 "jconfigint.h"
+#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);
+}