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/*
* jidctred-neon.c - reduced-size 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 F_0_211 1730
#define F_0_509 4176
#define F_0_601 4926
#define F_0_720 5906
#define F_0_765 6270
#define F_0_850 6967
#define F_0_899 7373
#define F_1_061 8697
#define F_1_272 10426
#define F_1_451 11893
#define F_1_847 15137
#define F_2_172 17799
#define F_2_562 20995
#define F_3_624 29692
/* jsimd_idct_2x2_neon() is an inverse DCT function that produces reduced-size
* 2x2 output from an 8x8 DCT block. It uses the same calculations and
* produces exactly the same output as IJG's original jpeg_idct_2x2() function
* from jpeg-6b, which can be found in jidctred.c.
*
* Scaled integer constants are used to avoid floating-point arithmetic:
* 0.720959822 = 5906 * 2^-13
* 0.850430095 = 6967 * 2^-13
* 1.272758580 = 10426 * 2^-13
* 3.624509785 = 29692 * 2^-13
*
* See jidctred.c for further details of the 2x2 IDCT algorithm. Where
* possible, the variable names and comments here in jsimd_idct_2x2_neon()
* match up with those in jpeg_idct_2x2().
*/
ALIGN(16) static const int16_t jsimd_idct_2x2_neon_consts[] = {
-F_0_720, F_0_850, -F_1_272, F_3_624
};
void jsimd_idct_2x2_neon(void *dct_table, JCOEFPTR coef_block,
JSAMPARRAY output_buf, JDIMENSION output_col)
{
ISLOW_MULT_TYPE *quantptr = dct_table;
/* Load DCT coefficients. */
int16x8_t row0 = vld1q_s16(coef_block + 0 * DCTSIZE);
int16x8_t row1 = vld1q_s16(coef_block + 1 * DCTSIZE);
int16x8_t row3 = vld1q_s16(coef_block + 3 * DCTSIZE);
int16x8_t row5 = vld1q_s16(coef_block + 5 * DCTSIZE);
int16x8_t row7 = vld1q_s16(coef_block + 7 * DCTSIZE);
/* Load quantization table values. */
int16x8_t quant_row0 = vld1q_s16(quantptr + 0 * DCTSIZE);
int16x8_t quant_row1 = vld1q_s16(quantptr + 1 * DCTSIZE);
int16x8_t quant_row3 = vld1q_s16(quantptr + 3 * DCTSIZE);
int16x8_t quant_row5 = vld1q_s16(quantptr + 5 * DCTSIZE);
int16x8_t quant_row7 = vld1q_s16(quantptr + 7 * DCTSIZE);
/* Dequantize DCT coefficients. */
row0 = vmulq_s16(row0, quant_row0);
row1 = vmulq_s16(row1, quant_row1);
row3 = vmulq_s16(row3, quant_row3);
row5 = vmulq_s16(row5, quant_row5);
row7 = vmulq_s16(row7, quant_row7);
/* Load IDCT conversion constants. */
const int16x4_t consts = vld1_s16(jsimd_idct_2x2_neon_consts);
/* Pass 1: process columns from input, put results in vectors row0 and
* row1.
*/
/* Even part */
int32x4_t tmp10_l = vshll_n_s16(vget_low_s16(row0), CONST_BITS + 2);
int32x4_t tmp10_h = vshll_n_s16(vget_high_s16(row0), CONST_BITS + 2);
/* Odd part */
int32x4_t tmp0_l = vmull_lane_s16(vget_low_s16(row1), consts, 3);
tmp0_l = vmlal_lane_s16(tmp0_l, vget_low_s16(row3), consts, 2);
tmp0_l = vmlal_lane_s16(tmp0_l, vget_low_s16(row5), consts, 1);
tmp0_l = vmlal_lane_s16(tmp0_l, vget_low_s16(row7), consts, 0);
int32x4_t tmp0_h = vmull_lane_s16(vget_high_s16(row1), consts, 3);
tmp0_h = vmlal_lane_s16(tmp0_h, vget_high_s16(row3), consts, 2);
tmp0_h = vmlal_lane_s16(tmp0_h, vget_high_s16(row5), consts, 1);
tmp0_h = vmlal_lane_s16(tmp0_h, vget_high_s16(row7), consts, 0);
/* Final output stage: descale and narrow to 16-bit. */
row0 = vcombine_s16(vrshrn_n_s32(vaddq_s32(tmp10_l, tmp0_l), CONST_BITS),
vrshrn_n_s32(vaddq_s32(tmp10_h, tmp0_h), CONST_BITS));
row1 = vcombine_s16(vrshrn_n_s32(vsubq_s32(tmp10_l, tmp0_l), CONST_BITS),
vrshrn_n_s32(vsubq_s32(tmp10_h, tmp0_h), CONST_BITS));
/* Transpose two rows, ready for second pass. */
int16x8x2_t cols_0246_1357 = vtrnq_s16(row0, row1);
int16x8_t cols_0246 = cols_0246_1357.val[0];
int16x8_t cols_1357 = cols_0246_1357.val[1];
/* Duplicate columns such that each is accessible in its own vector. */
int32x4x2_t cols_1155_3377 = vtrnq_s32(vreinterpretq_s32_s16(cols_1357),
vreinterpretq_s32_s16(cols_1357));
int16x8_t cols_1155 = vreinterpretq_s16_s32(cols_1155_3377.val[0]);
int16x8_t cols_3377 = vreinterpretq_s16_s32(cols_1155_3377.val[1]);
/* Pass 2: process two rows, store to output array. */
/* Even part: we're only interested in col0; the top half of tmp10 is "don't
* care."
*/
int32x4_t tmp10 = vshll_n_s16(vget_low_s16(cols_0246), CONST_BITS + 2);
/* Odd part: we're only interested in the bottom half of tmp0. */
int32x4_t tmp0 = vmull_lane_s16(vget_low_s16(cols_1155), consts, 3);
tmp0 = vmlal_lane_s16(tmp0, vget_low_s16(cols_3377), consts, 2);
tmp0 = vmlal_lane_s16(tmp0, vget_high_s16(cols_1155), consts, 1);
tmp0 = vmlal_lane_s16(tmp0, vget_high_s16(cols_3377), consts, 0);
/* Final output stage: descale and clamp to range [0-255]. */
int16x8_t output_s16 = vcombine_s16(vaddhn_s32(tmp10, tmp0),
vsubhn_s32(tmp10, tmp0));
output_s16 = vrsraq_n_s16(vdupq_n_s16(CENTERJSAMPLE), output_s16,
CONST_BITS + PASS1_BITS + 3 + 2 - 16);
/* Narrow to 8-bit and convert to unsigned. */
uint8x8_t output_u8 = vqmovun_s16(output_s16);
/* Store 2x2 block to memory. */
vst1_lane_u8(output_buf[0] + output_col, output_u8, 0);
vst1_lane_u8(output_buf[1] + output_col, output_u8, 1);
vst1_lane_u8(output_buf[0] + output_col + 1, output_u8, 4);
vst1_lane_u8(output_buf[1] + output_col + 1, output_u8, 5);
}
/* jsimd_idct_4x4_neon() is an inverse DCT function that produces reduced-size
* 4x4 output from an 8x8 DCT block. It uses the same calculations and
* produces exactly the same output as IJG's original jpeg_idct_4x4() function
* from jpeg-6b, which can be found in jidctred.c.
*
* Scaled integer constants are used to avoid floating-point arithmetic:
* 0.211164243 = 1730 * 2^-13
* 0.509795579 = 4176 * 2^-13
* 0.601344887 = 4926 * 2^-13
* 0.765366865 = 6270 * 2^-13
* 0.899976223 = 7373 * 2^-13
* 1.061594337 = 8697 * 2^-13
* 1.451774981 = 11893 * 2^-13
* 1.847759065 = 15137 * 2^-13
* 2.172734803 = 17799 * 2^-13
* 2.562915447 = 20995 * 2^-13
*
* See jidctred.c for further details of the 4x4 IDCT algorithm. Where
* possible, the variable names and comments here in jsimd_idct_4x4_neon()
* match up with those in jpeg_idct_4x4().
*/
ALIGN(16) static const int16_t jsimd_idct_4x4_neon_consts[] = {
F_1_847, -F_0_765, -F_0_211, F_1_451,
-F_2_172, F_1_061, -F_0_509, -F_0_601,
F_0_899, F_2_562, 0, 0
};
void jsimd_idct_4x4_neon(void *dct_table, JCOEFPTR coef_block,
JSAMPARRAY output_buf, JDIMENSION output_col)
{
ISLOW_MULT_TYPE *quantptr = dct_table;
/* Load DCT coefficients. */
int16x8_t row0 = vld1q_s16(coef_block + 0 * DCTSIZE);
int16x8_t row1 = vld1q_s16(coef_block + 1 * DCTSIZE);
int16x8_t row2 = vld1q_s16(coef_block + 2 * DCTSIZE);
int16x8_t row3 = vld1q_s16(coef_block + 3 * DCTSIZE);
int16x8_t row5 = vld1q_s16(coef_block + 5 * DCTSIZE);
int16x8_t row6 = vld1q_s16(coef_block + 6 * DCTSIZE);
int16x8_t row7 = vld1q_s16(coef_block + 7 * DCTSIZE);
/* Load quantization table values for DC coefficients. */
int16x8_t quant_row0 = vld1q_s16(quantptr + 0 * DCTSIZE);
/* Dequantize DC coefficients. */
row0 = vmulq_s16(row0, quant_row0);
/* Construct bitmap to test if all AC coefficients are 0. */
int16x8_t bitmap = vorrq_s16(row1, row2);
bitmap = vorrq_s16(bitmap, row3);
bitmap = vorrq_s16(bitmap, row5);
bitmap = vorrq_s16(bitmap, row6);
bitmap = vorrq_s16(bitmap, row7);
int64_t left_ac_bitmap = vgetq_lane_s64(vreinterpretq_s64_s16(bitmap), 0);
int64_t right_ac_bitmap = vgetq_lane_s64(vreinterpretq_s64_s16(bitmap), 1);
/* Load constants for IDCT computation. */
#ifdef HAVE_VLD1_S16_X3
const int16x4x3_t consts = vld1_s16_x3(jsimd_idct_4x4_neon_consts);
#else
/* GCC does not currently support the intrinsic vld1_<type>_x3(). */
const int16x4_t consts1 = vld1_s16(jsimd_idct_4x4_neon_consts);
const int16x4_t consts2 = vld1_s16(jsimd_idct_4x4_neon_consts + 4);
const int16x4_t consts3 = vld1_s16(jsimd_idct_4x4_neon_consts + 8);
const int16x4x3_t consts = { { consts1, consts2, consts3 } };
#endif
if (left_ac_bitmap == 0 && right_ac_bitmap == 0) {
/* All AC coefficients are zero.
* Compute DC values and duplicate into row vectors 0, 1, 2, and 3.
*/
int16x8_t dcval = vshlq_n_s16(row0, PASS1_BITS);
row0 = dcval;
row1 = dcval;
row2 = dcval;
row3 = dcval;
} else if (left_ac_bitmap == 0) {
/* AC coefficients are zero for columns 0, 1, 2, and 3.
* Compute DC values for these columns.
*/
int16x4_t dcval = vshl_n_s16(vget_low_s16(row0), PASS1_BITS);
/* Commence regular IDCT computation for columns 4, 5, 6, and 7. */
/* Load quantization table. */
int16x4_t quant_row1 = vld1_s16(quantptr + 1 * DCTSIZE + 4);
int16x4_t quant_row2 = vld1_s16(quantptr + 2 * DCTSIZE + 4);
int16x4_t quant_row3 = vld1_s16(quantptr + 3 * DCTSIZE + 4);
int16x4_t quant_row5 = vld1_s16(quantptr + 5 * DCTSIZE + 4);
int16x4_t quant_row6 = vld1_s16(quantptr + 6 * DCTSIZE + 4);
int16x4_t quant_row7 = vld1_s16(quantptr + 7 * DCTSIZE + 4);
/* Even part */
int32x4_t tmp0 = vshll_n_s16(vget_high_s16(row0), CONST_BITS + 1);
int16x4_t z2 = vmul_s16(vget_high_s16(row2), quant_row2);
int16x4_t z3 = vmul_s16(vget_high_s16(row6), quant_row6);
int32x4_t tmp2 = vmull_lane_s16(z2, consts.val[0], 0);
tmp2 = vmlal_lane_s16(tmp2, z3, consts.val[0], 1);
int32x4_t tmp10 = vaddq_s32(tmp0, tmp2);
int32x4_t tmp12 = vsubq_s32(tmp0, tmp2);
/* Odd part */
int16x4_t z1 = vmul_s16(vget_high_s16(row7), quant_row7);
z2 = vmul_s16(vget_high_s16(row5), quant_row5);
z3 = vmul_s16(vget_high_s16(row3), quant_row3);
int16x4_t z4 = vmul_s16(vget_high_s16(row1), quant_row1);
tmp0 = vmull_lane_s16(z1, consts.val[0], 2);
tmp0 = vmlal_lane_s16(tmp0, z2, consts.val[0], 3);
tmp0 = vmlal_lane_s16(tmp0, z3, consts.val[1], 0);
tmp0 = vmlal_lane_s16(tmp0, z4, consts.val[1], 1);
tmp2 = vmull_lane_s16(z1, consts.val[1], 2);
tmp2 = vmlal_lane_s16(tmp2, z2, consts.val[1], 3);
tmp2 = vmlal_lane_s16(tmp2, z3, consts.val[2], 0);
tmp2 = vmlal_lane_s16(tmp2, z4, consts.val[2], 1);
/* Final output stage: descale and narrow to 16-bit. */
row0 = vcombine_s16(dcval, vrshrn_n_s32(vaddq_s32(tmp10, tmp2),
CONST_BITS - PASS1_BITS + 1));
row3 = vcombine_s16(dcval, vrshrn_n_s32(vsubq_s32(tmp10, tmp2),
CONST_BITS - PASS1_BITS + 1));
row1 = vcombine_s16(dcval, vrshrn_n_s32(vaddq_s32(tmp12, tmp0),
CONST_BITS - PASS1_BITS + 1));
row2 = vcombine_s16(dcval, vrshrn_n_s32(vsubq_s32(tmp12, tmp0),
CONST_BITS - PASS1_BITS + 1));
} else if (right_ac_bitmap == 0) {
/* AC coefficients are zero for columns 4, 5, 6, and 7.
* Compute DC values for these columns.
*/
int16x4_t dcval = vshl_n_s16(vget_high_s16(row0), PASS1_BITS);
/* Commence regular IDCT computation for columns 0, 1, 2, and 3. */
/* Load quantization table. */
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_row5 = vld1_s16(quantptr + 5 * DCTSIZE);
int16x4_t quant_row6 = vld1_s16(quantptr + 6 * DCTSIZE);
int16x4_t quant_row7 = vld1_s16(quantptr + 7 * DCTSIZE);
/* Even part */
int32x4_t tmp0 = vshll_n_s16(vget_low_s16(row0), CONST_BITS + 1);
int16x4_t z2 = vmul_s16(vget_low_s16(row2), quant_row2);
int16x4_t z3 = vmul_s16(vget_low_s16(row6), quant_row6);
int32x4_t tmp2 = vmull_lane_s16(z2, consts.val[0], 0);
tmp2 = vmlal_lane_s16(tmp2, z3, consts.val[0], 1);
int32x4_t tmp10 = vaddq_s32(tmp0, tmp2);
int32x4_t tmp12 = vsubq_s32(tmp0, tmp2);
/* Odd part */
int16x4_t z1 = vmul_s16(vget_low_s16(row7), quant_row7);
z2 = vmul_s16(vget_low_s16(row5), quant_row5);
z3 = vmul_s16(vget_low_s16(row3), quant_row3);
int16x4_t z4 = vmul_s16(vget_low_s16(row1), quant_row1);
tmp0 = vmull_lane_s16(z1, consts.val[0], 2);
tmp0 = vmlal_lane_s16(tmp0, z2, consts.val[0], 3);
tmp0 = vmlal_lane_s16(tmp0, z3, consts.val[1], 0);
tmp0 = vmlal_lane_s16(tmp0, z4, consts.val[1], 1);
tmp2 = vmull_lane_s16(z1, consts.val[1], 2);
tmp2 = vmlal_lane_s16(tmp2, z2, consts.val[1], 3);
tmp2 = vmlal_lane_s16(tmp2, z3, consts.val[2], 0);
tmp2 = vmlal_lane_s16(tmp2, z4, consts.val[2], 1);
/* Final output stage: descale and narrow to 16-bit. */
row0 = vcombine_s16(vrshrn_n_s32(vaddq_s32(tmp10, tmp2),
CONST_BITS - PASS1_BITS + 1), dcval);
row3 = vcombine_s16(vrshrn_n_s32(vsubq_s32(tmp10, tmp2),
CONST_BITS - PASS1_BITS + 1), dcval);
row1 = vcombine_s16(vrshrn_n_s32(vaddq_s32(tmp12, tmp0),
CONST_BITS - PASS1_BITS + 1), dcval);
row2 = vcombine_s16(vrshrn_n_s32(vsubq_s32(tmp12, tmp0),
CONST_BITS - PASS1_BITS + 1), dcval);
} else {
/* All AC coefficients are non-zero; full IDCT calculation required. */
int16x8_t quant_row1 = vld1q_s16(quantptr + 1 * DCTSIZE);
int16x8_t quant_row2 = vld1q_s16(quantptr + 2 * DCTSIZE);
int16x8_t quant_row3 = vld1q_s16(quantptr + 3 * DCTSIZE);
int16x8_t quant_row5 = vld1q_s16(quantptr + 5 * DCTSIZE);
int16x8_t quant_row6 = vld1q_s16(quantptr + 6 * DCTSIZE);
int16x8_t quant_row7 = vld1q_s16(quantptr + 7 * DCTSIZE);
/* Even part */
int32x4_t tmp0_l = vshll_n_s16(vget_low_s16(row0), CONST_BITS + 1);
int32x4_t tmp0_h = vshll_n_s16(vget_high_s16(row0), CONST_BITS + 1);
int16x8_t z2 = vmulq_s16(row2, quant_row2);
int16x8_t z3 = vmulq_s16(row6, quant_row6);
int32x4_t tmp2_l = vmull_lane_s16(vget_low_s16(z2), consts.val[0], 0);
int32x4_t tmp2_h = vmull_lane_s16(vget_high_s16(z2), consts.val[0], 0);
tmp2_l = vmlal_lane_s16(tmp2_l, vget_low_s16(z3), consts.val[0], 1);
tmp2_h = vmlal_lane_s16(tmp2_h, vget_high_s16(z3), consts.val[0], 1);
int32x4_t tmp10_l = vaddq_s32(tmp0_l, tmp2_l);
int32x4_t tmp10_h = vaddq_s32(tmp0_h, tmp2_h);
int32x4_t tmp12_l = vsubq_s32(tmp0_l, tmp2_l);
int32x4_t tmp12_h = vsubq_s32(tmp0_h, tmp2_h);
/* Odd part */
int16x8_t z1 = vmulq_s16(row7, quant_row7);
z2 = vmulq_s16(row5, quant_row5);
z3 = vmulq_s16(row3, quant_row3);
int16x8_t z4 = vmulq_s16(row1, quant_row1);
tmp0_l = vmull_lane_s16(vget_low_s16(z1), consts.val[0], 2);
tmp0_l = vmlal_lane_s16(tmp0_l, vget_low_s16(z2), consts.val[0], 3);
tmp0_l = vmlal_lane_s16(tmp0_l, vget_low_s16(z3), consts.val[1], 0);
tmp0_l = vmlal_lane_s16(tmp0_l, vget_low_s16(z4), consts.val[1], 1);
tmp0_h = vmull_lane_s16(vget_high_s16(z1), consts.val[0], 2);
tmp0_h = vmlal_lane_s16(tmp0_h, vget_high_s16(z2), consts.val[0], 3);
tmp0_h = vmlal_lane_s16(tmp0_h, vget_high_s16(z3), consts.val[1], 0);
tmp0_h = vmlal_lane_s16(tmp0_h, vget_high_s16(z4), consts.val[1], 1);
tmp2_l = vmull_lane_s16(vget_low_s16(z1), consts.val[1], 2);
tmp2_l = vmlal_lane_s16(tmp2_l, vget_low_s16(z2), consts.val[1], 3);
tmp2_l = vmlal_lane_s16(tmp2_l, vget_low_s16(z3), consts.val[2], 0);
tmp2_l = vmlal_lane_s16(tmp2_l, vget_low_s16(z4), consts.val[2], 1);
tmp2_h = vmull_lane_s16(vget_high_s16(z1), consts.val[1], 2);
tmp2_h = vmlal_lane_s16(tmp2_h, vget_high_s16(z2), consts.val[1], 3);
tmp2_h = vmlal_lane_s16(tmp2_h, vget_high_s16(z3), consts.val[2], 0);
tmp2_h = vmlal_lane_s16(tmp2_h, vget_high_s16(z4), consts.val[2], 1);
/* Final output stage: descale and narrow to 16-bit. */
row0 = vcombine_s16(vrshrn_n_s32(vaddq_s32(tmp10_l, tmp2_l),
CONST_BITS - PASS1_BITS + 1),
vrshrn_n_s32(vaddq_s32(tmp10_h, tmp2_h),
CONST_BITS - PASS1_BITS + 1));
row3 = vcombine_s16(vrshrn_n_s32(vsubq_s32(tmp10_l, tmp2_l),
CONST_BITS - PASS1_BITS + 1),
vrshrn_n_s32(vsubq_s32(tmp10_h, tmp2_h),
CONST_BITS - PASS1_BITS + 1));
row1 = vcombine_s16(vrshrn_n_s32(vaddq_s32(tmp12_l, tmp0_l),
CONST_BITS - PASS1_BITS + 1),
vrshrn_n_s32(vaddq_s32(tmp12_h, tmp0_h),
CONST_BITS - PASS1_BITS + 1));
row2 = vcombine_s16(vrshrn_n_s32(vsubq_s32(tmp12_l, tmp0_l),
CONST_BITS - PASS1_BITS + 1),
vrshrn_n_s32(vsubq_s32(tmp12_h, tmp0_h),
CONST_BITS - PASS1_BITS + 1));
}
/* Transpose 8x4 block to perform IDCT on rows in second pass. */
int16x8x2_t row_01 = vtrnq_s16(row0, row1);
int16x8x2_t row_23 = vtrnq_s16(row2, row3);
int32x4x2_t cols_0426 = vtrnq_s32(vreinterpretq_s32_s16(row_01.val[0]),
vreinterpretq_s32_s16(row_23.val[0]));
int32x4x2_t cols_1537 = vtrnq_s32(vreinterpretq_s32_s16(row_01.val[1]),
vreinterpretq_s32_s16(row_23.val[1]));
int16x4_t col0 = vreinterpret_s16_s32(vget_low_s32(cols_0426.val[0]));
int16x4_t col1 = vreinterpret_s16_s32(vget_low_s32(cols_1537.val[0]));
int16x4_t col2 = vreinterpret_s16_s32(vget_low_s32(cols_0426.val[1]));
int16x4_t col3 = vreinterpret_s16_s32(vget_low_s32(cols_1537.val[1]));
int16x4_t col5 = vreinterpret_s16_s32(vget_high_s32(cols_1537.val[0]));
int16x4_t col6 = vreinterpret_s16_s32(vget_high_s32(cols_0426.val[1]));
int16x4_t col7 = vreinterpret_s16_s32(vget_high_s32(cols_1537.val[1]));
/* Commence second pass of IDCT. */
/* Even part */
int32x4_t tmp0 = vshll_n_s16(col0, CONST_BITS + 1);
int32x4_t tmp2 = vmull_lane_s16(col2, consts.val[0], 0);
tmp2 = vmlal_lane_s16(tmp2, col6, consts.val[0], 1);
int32x4_t tmp10 = vaddq_s32(tmp0, tmp2);
int32x4_t tmp12 = vsubq_s32(tmp0, tmp2);
/* Odd part */
tmp0 = vmull_lane_s16(col7, consts.val[0], 2);
tmp0 = vmlal_lane_s16(tmp0, col5, consts.val[0], 3);
tmp0 = vmlal_lane_s16(tmp0, col3, consts.val[1], 0);
tmp0 = vmlal_lane_s16(tmp0, col1, consts.val[1], 1);
tmp2 = vmull_lane_s16(col7, consts.val[1], 2);
tmp2 = vmlal_lane_s16(tmp2, col5, consts.val[1], 3);
tmp2 = vmlal_lane_s16(tmp2, col3, consts.val[2], 0);
tmp2 = vmlal_lane_s16(tmp2, col1, consts.val[2], 1);
/* Final output stage: descale and clamp to range [0-255]. */
int16x8_t output_cols_02 = vcombine_s16(vaddhn_s32(tmp10, tmp2),
vsubhn_s32(tmp12, tmp0));
int16x8_t output_cols_13 = vcombine_s16(vaddhn_s32(tmp12, tmp0),
vsubhn_s32(tmp10, tmp2));
output_cols_02 = vrsraq_n_s16(vdupq_n_s16(CENTERJSAMPLE), output_cols_02,
CONST_BITS + PASS1_BITS + 3 + 1 - 16);
output_cols_13 = vrsraq_n_s16(vdupq_n_s16(CENTERJSAMPLE), output_cols_13,
CONST_BITS + PASS1_BITS + 3 + 1 - 16);
/* Narrow to 8-bit and convert to unsigned while zipping 8-bit elements.
* An interleaving store completes the transpose.
*/
uint8x8x2_t output_0123 = vzip_u8(vqmovun_s16(output_cols_02),
vqmovun_s16(output_cols_13));
uint16x4x2_t output_01_23 = { {
vreinterpret_u16_u8(output_0123.val[0]),
vreinterpret_u16_u8(output_0123.val[1])
} };
/* Store 4x4 block to memory. */
JSAMPROW outptr0 = output_buf[0] + output_col;
JSAMPROW outptr1 = output_buf[1] + output_col;
JSAMPROW outptr2 = output_buf[2] + output_col;
JSAMPROW outptr3 = output_buf[3] + output_col;
vst2_lane_u16((uint16_t *)outptr0, output_01_23, 0);
vst2_lane_u16((uint16_t *)outptr1, output_01_23, 1);
vst2_lane_u16((uint16_t *)outptr2, output_01_23, 2);
vst2_lane_u16((uint16_t *)outptr3, output_01_23, 3);
}
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