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added IDCT rvv code from Andes #2

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377 changes: 377 additions & 0 deletions simd/rvv_andes/jidctfst-rvv.c
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/*
* jidctfst-rvv.c - fast integer IDCT (RISC-V RVV)
*
* Copyright (c) 2012-2024 Andes Technology Corporation
* All rights reserved.
*/
/*
* jidctfst-neon.c - fast integer IDCT (Arm Neon)
*
* Copyright (C) 2020, Arm Limited. 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 <riscv_vector.h>


/* jsimd_idct_ifast_rvv() performs dequantization and a fast, not so accurate
* inverse DCT (Discrete Cosine Transform) on one block of coefficients. It
* uses the same calculations and produces exactly the same output as IJG's
* original jpeg_idct_ifast() function, which can be found in jidctfst.c.
*
* Scaled integer constants are used to avoid floating-point arithmetic:
* 0.082392200 = 2688 * 2^-15
* 0.414213562 = 13568 * 2^-15
* 0.847759065 = 27776 * 2^-15
* 0.613125930 = 20096 * 2^-15
*
* See jidctfst.c for further details of the IDCT algorithm. Where possible,
* the variable names and comments here in jsimd_idct_ifast_rvv() match up
* with those in jpeg_idct_ifast().
*/

#define PASS1_BITS 2

#define F_0_082 2688
#define F_0_414 13568
#define F_0_847 27776
#define F_0_613 20096


static const int16_t idct_ifast_consts[] = {
F_0_082, F_0_414, F_0_847, F_0_613
};

void jsimd_idct_ifast_rvv(void *dct_table, JCOEFPTR coef_block,
JSAMPARRAY output_buf, JDIMENSION output_col)
{
IFAST_MULT_TYPE *quantptr = dct_table;
vint16m8_t rows_all_i16m8;

/* Load DCT coefficients. */
size_t vl = 8;
vint16m1_t row0 = __riscv_vle16_v_i16m1(coef_block + 0 * DCTSIZE, vl);
vint16m1_t row1 = __riscv_vle16_v_i16m1(coef_block + 1 * DCTSIZE, vl);
vint16m1_t row2 = __riscv_vle16_v_i16m1(coef_block + 2 * DCTSIZE, vl);
vint16m1_t row3 = __riscv_vle16_v_i16m1(coef_block + 3 * DCTSIZE, vl);
vint16m1_t row4 = __riscv_vle16_v_i16m1(coef_block + 4 * DCTSIZE, vl);
vint16m1_t row5 = __riscv_vle16_v_i16m1(coef_block + 5 * DCTSIZE, vl);
vint16m1_t row6 = __riscv_vle16_v_i16m1(coef_block + 6 * DCTSIZE, vl);
vint16m1_t row7 = __riscv_vle16_v_i16m1(coef_block + 7 * DCTSIZE, vl);

/* Load quantization table values for DC coefficients. */
vint16m1_t quant_row0 = __riscv_vle16_v_i16m1(quantptr + 0 * DCTSIZE, vl);

/* Dequantize DC coefficients. */
row0 = __riscv_vmul_vv_i16m1(row0, quant_row0, vl);

/* Construct bitmap to test if all AC coefficients are 0. */
vint16m1_t bitmap = __riscv_vor_vv_i16m1(row1, row2, vl);
bitmap = __riscv_vor_vv_i16m1(bitmap, row3, vl);
bitmap = __riscv_vor_vv_i16m1(bitmap, row4, vl);
bitmap = __riscv_vor_vv_i16m1(bitmap, row5, vl);
bitmap = __riscv_vor_vv_i16m1(bitmap, row6, vl);
bitmap = __riscv_vor_vv_i16m1(bitmap, row7, vl);

uint16_t ac_bitmap;
{
vuint16m1_t vec_zero = __riscv_vmv_s_x_u16m1(0, vl);
vuint16m1_t tmp_u16m1 = __riscv_vreinterpret_v_i16m1_u16m1(bitmap);
ac_bitmap = __riscv_vmv_x_s_u16m1_u16(__riscv_vredor_vs_u16m1_u16m1(tmp_u16m1, vec_zero, vl));
}

/* Load IDCT conversion constants. */
if (0 == ac_bitmap)
{
/* All AC coefficients are zero.
* Compute DC values and duplicate into vectors.
*/
// combine vectors
vint16m4_t tmp_i16m4 = __riscv_vlmul_ext_v_i16m1_i16m4(row0);
tmp_i16m4 = __riscv_vslideup_vx_i16m4(tmp_i16m4, tmp_i16m4, DCTSIZE2/8, DCTSIZE2/4);
tmp_i16m4 = __riscv_vslideup_vx_i16m4(tmp_i16m4, tmp_i16m4, DCTSIZE2/4, DCTSIZE2/2);
rows_all_i16m8 = __riscv_vlmul_ext_v_i16m4_i16m8(tmp_i16m4);
rows_all_i16m8 = __riscv_vslideup_vx_i16m8(rows_all_i16m8, rows_all_i16m8, DCTSIZE2/2, DCTSIZE2);
}
else {
/* full IDCT calculation. */

/* Load quantization table. */
vint16m1_t quant_row1 = __riscv_vle16_v_i16m1(quantptr + 1 * DCTSIZE, vl);
vint16m1_t quant_row2 = __riscv_vle16_v_i16m1(quantptr + 2 * DCTSIZE, vl);
vint16m1_t quant_row3 = __riscv_vle16_v_i16m1(quantptr + 3 * DCTSIZE, vl);
vint16m1_t quant_row4 = __riscv_vle16_v_i16m1(quantptr + 4 * DCTSIZE, vl);
vint16m1_t quant_row5 = __riscv_vle16_v_i16m1(quantptr + 5 * DCTSIZE, vl);
vint16m1_t quant_row6 = __riscv_vle16_v_i16m1(quantptr + 6 * DCTSIZE, vl);
vint16m1_t quant_row7 = __riscv_vle16_v_i16m1(quantptr + 7 * DCTSIZE, vl);

/* Even part: dequantize DCT coefficients. */
vint16m1_t tmp0 = __riscv_vmv_v_v_i16m1(row0, vl);
vint16m1_t tmp1 = __riscv_vmul_vv_i16m1(row2, quant_row2, vl);
vint16m1_t tmp2 = __riscv_vmul_vv_i16m1(row4, quant_row4, vl);
vint16m1_t tmp3 = __riscv_vmul_vv_i16m1(row6, quant_row6, vl);

vint16m1_t tmp10 = __riscv_vadd_vv_i16m1(tmp0, tmp2, vl); /* phase 3 */
vint16m1_t tmp11 = __riscv_vsub_vv_i16m1(tmp0, tmp2, vl);
vint16m1_t tmp13 = __riscv_vadd_vv_i16m1(tmp1, tmp3, vl); /* phases 5-3 */
vint16m1_t tmp12;
{
vint16m1_t tmp1_sub_tmp3 = __riscv_vsub_vv_i16m1(tmp1, tmp3, vl);
tmp12 = __riscv_vsmul_vx_i16m1(tmp1_sub_tmp3, idct_ifast_consts[1], vl);
tmp12 = __riscv_vadd_vv_i16m1(tmp12, tmp1_sub_tmp3, vl);
tmp12 = __riscv_vsub_vv_i16m1(tmp12, tmp13, vl);
}

tmp0 = __riscv_vadd_vv_i16m1(tmp10, tmp13, vl); /* phase 2 */
tmp3 = __riscv_vsub_vv_i16m1(tmp10, tmp13, vl);
tmp1 = __riscv_vadd_vv_i16m1(tmp11, tmp12, vl);
tmp2 = __riscv_vsub_vv_i16m1(tmp11, tmp12, vl);

/* Odd part: dequantize DCT coefficients. */
vint16m1_t tmp4 = __riscv_vmul_vv_i16m1(__riscv_vmv_v_v_i16m1(row1, vl), quant_row1, vl);
vint16m1_t tmp5 = __riscv_vmul_vv_i16m1(__riscv_vmv_v_v_i16m1(row3, vl), quant_row3, vl);
vint16m1_t tmp6 = __riscv_vmul_vv_i16m1(__riscv_vmv_v_v_i16m1(row5, vl), quant_row5, vl);
vint16m1_t tmp7 = __riscv_vmul_vv_i16m1(__riscv_vmv_v_v_i16m1(row7, vl), quant_row7, vl);

vint16m1_t z13 = __riscv_vadd_vv_i16m1(tmp5, tmp6, vl); /* phase 6 */
vint16m1_t neg_z10 = __riscv_vsub_vv_i16m1(tmp5, tmp6, vl);
vint16m1_t z11 = __riscv_vadd_vv_i16m1(tmp4, tmp7, vl);
vint16m1_t z12 = __riscv_vsub_vv_i16m1(tmp4, tmp7, vl);

tmp7 = __riscv_vadd_vv_i16m1(z11, z13, vl); /* phase 5 */
{
vint16m1_t z11_sub_z13 = __riscv_vsub_vv_i16m1(z11, z13, vl);
tmp11 = __riscv_vsmul_vx_i16m1(z11_sub_z13, idct_ifast_consts[1], vl);
tmp11 = __riscv_vadd_vv_i16m1(tmp11, z11_sub_z13, vl);
}

{
vint16m1_t z10_add_z12 = __riscv_vsub_vv_i16m1(z12, neg_z10, vl);
vint16m1_t z5 = __riscv_vsmul_vx_i16m1(z10_add_z12, idct_ifast_consts[2], vl);
z5 = __riscv_vadd_vv_i16m1(z5, z10_add_z12, vl);

tmp10 = __riscv_vsmul_vx_i16m1(z12, idct_ifast_consts[0], vl);
tmp10 = __riscv_vadd_vv_i16m1(tmp10, z12, vl);
tmp10 = __riscv_vsub_vv_i16m1(tmp10, z5, vl);

tmp12 = __riscv_vsmul_vx_i16m1(neg_z10, idct_ifast_consts[3], vl);
vint16m1_t tmp_neg_z10_d = __riscv_vadd_vv_i16m1(neg_z10, neg_z10, vl);
tmp12 = __riscv_vadd_vv_i16m1(tmp12, tmp_neg_z10_d, vl);
tmp12 = __riscv_vadd_vv_i16m1(tmp12, z5, vl);
}

tmp6 = __riscv_vsub_vv_i16m1(tmp12, tmp7, vl); /* phase 2 */
tmp5 = __riscv_vsub_vv_i16m1(tmp11, tmp6, vl);
tmp4 = __riscv_vadd_vv_i16m1(tmp10, tmp5, vl);

row0 = __riscv_vadd_vv_i16m1(tmp0, tmp7, vl);
row7 = __riscv_vsub_vv_i16m1(tmp0, tmp7, vl);
row1 = __riscv_vadd_vv_i16m1(tmp1, tmp6, vl);
row6 = __riscv_vsub_vv_i16m1(tmp1, tmp6, vl);
row2 = __riscv_vadd_vv_i16m1(tmp2, tmp5, vl);
row5 = __riscv_vsub_vv_i16m1(tmp2, tmp5, vl);
row4 = __riscv_vadd_vv_i16m1(tmp3, tmp4, vl);
row3 = __riscv_vsub_vv_i16m1(tmp3, tmp4, vl);

// combine vectors
vint16m4_t rows_0123_i16m4 = __riscv_vlmul_ext_v_i16m1_i16m4(row0);
rows_0123_i16m4 = __riscv_vslideup_vx_i16m4(rows_0123_i16m4, __riscv_vlmul_ext_v_i16m1_i16m4(row1), 8, 32);
rows_0123_i16m4 = __riscv_vslideup_vx_i16m4(rows_0123_i16m4, __riscv_vlmul_ext_v_i16m1_i16m4(row2), 16, 32);
rows_0123_i16m4 = __riscv_vslideup_vx_i16m4(rows_0123_i16m4, __riscv_vlmul_ext_v_i16m1_i16m4(row2), 24, 32);

vint16m4_t rows_4567_i16m4 = __riscv_vlmul_ext_v_i16m1_i16m4(row4);
rows_4567_i16m4 = __riscv_vslideup_vx_i16m4(rows_4567_i16m4, __riscv_vlmul_ext_v_i16m1_i16m4(row5), 8, 32);
rows_4567_i16m4 = __riscv_vslideup_vx_i16m4(rows_4567_i16m4, __riscv_vlmul_ext_v_i16m1_i16m4(row6), 16, 32);
rows_4567_i16m4 = __riscv_vslideup_vx_i16m4(rows_4567_i16m4, __riscv_vlmul_ext_v_i16m1_i16m4(row7), 24, 32);

rows_all_i16m8 = __riscv_vlmul_ext_v_i16m4_i16m8(rows_0123_i16m4);
rows_all_i16m8 = __riscv_vslideup_vx_i16m8(rows_all_i16m8, __riscv_vlmul_ext_v_i16m4_i16m8(rows_4567_i16m4), 32, 64);
}

/* Transpose rows to work on columns in pass 2. */
const uint8_t trans_index8x8_u8[DCTSIZE2] =
{
0, 8, 16, 24, 32, 40, 48, 56,
1, 9, 17, 25, 33, 41, 49, 57,
2, 10, 18, 26, 34, 42, 50, 58,
3, 11, 19, 27, 35, 43, 51, 59,
4, 12, 20, 28, 36, 44, 52, 60,
5, 13, 21, 29, 37, 45, 53, 61,
6, 14, 22, 30, 38, 46, 54, 62,
7, 15, 23, 31, 39, 47, 55, 63,
};

// load transpose look-up table
vuint8m4_t vg_reg8 = __riscv_vle8_v_u8m4(trans_index8x8_u8, DCTSIZE2);

// interpret to u16 & transpose
vint16m8_t vg_reg16 = __riscv_vrgather(rows_all_i16m8, __riscv_vzext_vf2_u16m8(vg_reg8, DCTSIZE2), \
DCTSIZE2);
int16_t workspace[DCTSIZE2]; /* buffers data between passes */
__riscv_vse16_v_i16m8(&workspace[0], vg_reg16, DCTSIZE2);
vint16m1_t col0 = __riscv_vle16_v_i16m1(&workspace[8*0], vl);
vint16m1_t col1 = __riscv_vle16_v_i16m1(&workspace[8*1], vl);
vint16m1_t col2 = __riscv_vle16_v_i16m1(&workspace[8*2], vl);
vint16m1_t col3 = __riscv_vle16_v_i16m1(&workspace[8*3], vl);
vint16m1_t col4 = __riscv_vle16_v_i16m1(&workspace[8*4], vl);
vint16m1_t col5 = __riscv_vle16_v_i16m1(&workspace[8*5], vl);
vint16m1_t col6 = __riscv_vle16_v_i16m1(&workspace[8*6], vl);
vint16m1_t col7 = __riscv_vle16_v_i16m1(&workspace[8*7], vl);

/* 1-D IDCT, pass 2 */

/* Even part */
vint16m1_t tmp10 = __riscv_vadd_vv_i16m1(col0, col4, vl);
vint16m1_t tmp11 = __riscv_vsub_vv_i16m1(col0, col4, vl);
vint16m1_t tmp13 = __riscv_vadd_vv_i16m1(col2, col6, vl);
vint16m1_t tmp12;
{
vint16m1_t col2_sub_col6 = __riscv_vsub_vv_i16m1(col2, col6, vl);
tmp12 = __riscv_vsmul_vx_i16m1(col2_sub_col6, idct_ifast_consts[1], vl);
tmp12 = __riscv_vadd_vv_i16m1(tmp12, col2_sub_col6, vl);
tmp12 = __riscv_vsub_vv_i16m1(tmp12, tmp13, vl);
}

vint16m1_t tmp0 = __riscv_vadd_vv_i16m1(tmp10, tmp13, vl);
vint16m1_t tmp3 = __riscv_vsub_vv_i16m1(tmp10, tmp13, vl);
vint16m1_t tmp1 = __riscv_vadd_vv_i16m1(tmp11, tmp12, vl);
vint16m1_t tmp2 = __riscv_vsub_vv_i16m1(tmp11, tmp12, vl);

/* Odd part */
vint16m1_t z13 = __riscv_vadd_vv_i16m1(col5, col3, vl);
vint16m1_t neg_z10 = __riscv_vsub_vv_i16m1(col3, col5, vl);
vint16m1_t z11 = __riscv_vadd_vv_i16m1(col1, col7, vl);
vint16m1_t z12 = __riscv_vsub_vv_i16m1(col1, col7, vl);

vint16m1_t tmp7 = __riscv_vadd_vv_i16m1(z11, z13, vl); /* phase 5 */
{
vint16m1_t z11_sub_z13 = __riscv_vsub_vv_i16m1(z11, z13, vl);
tmp11 = __riscv_vsmul_vx_i16m1(z11_sub_z13, idct_ifast_consts[1], vl);
tmp11 = __riscv_vadd_vv_i16m1(tmp11, z11_sub_z13, vl);
}

{
vint16m1_t z10_add_z12 = __riscv_vsub_vv_i16m1(z12, neg_z10, vl);
vint16m1_t z5 = __riscv_vsmul_vx_i16m1(z10_add_z12, idct_ifast_consts[2], vl);
z5 = __riscv_vadd_vv_i16m1(z5, z10_add_z12, vl);

tmp10 = __riscv_vsmul_vx_i16m1(z12, idct_ifast_consts[0], vl);
tmp10 = __riscv_vadd_vv_i16m1(tmp10, z12, vl);
tmp10 = __riscv_vsub_vv_i16m1(tmp10, z5, vl);

tmp12 = __riscv_vsmul_vx_i16m1(neg_z10, idct_ifast_consts[3], vl);
vint16m1_t tmp_neg_z10_d = __riscv_vadd_vv_i16m1(neg_z10, neg_z10, vl);
tmp12 = __riscv_vadd_vv_i16m1(tmp12, tmp_neg_z10_d, vl);
tmp12 = __riscv_vadd_vv_i16m1(tmp12, z5, vl);
}

vint16m1_t tmp6 = __riscv_vsub_vv_i16m1(tmp12, tmp7, vl); /* phase 2 */
vint16m1_t tmp5 = __riscv_vsub_vv_i16m1(tmp11, tmp6, vl);
vint16m1_t tmp4 = __riscv_vadd_vv_i16m1(tmp10, tmp5, vl);

col0 = __riscv_vadd_vv_i16m1(tmp0, tmp7, vl);
col7 = __riscv_vsub_vv_i16m1(tmp0, tmp7, vl);
col1 = __riscv_vadd_vv_i16m1(tmp1, tmp6, vl);
col6 = __riscv_vsub_vv_i16m1(tmp1, tmp6, vl);
col2 = __riscv_vadd_vv_i16m1(tmp2, tmp5, vl);
col5 = __riscv_vsub_vv_i16m1(tmp2, tmp5, vl);
col4 = __riscv_vadd_vv_i16m1(tmp3, tmp4, vl);
col3 = __riscv_vsub_vv_i16m1(tmp3, tmp4, vl);

/* Scale down by a factor of 8, narrowing to 8-bit. */
/* Clamp to range [0-255]. */
vint8m2_t tmp_i8m2;
vuint8m2_t u8m2_col0123, u8m2_col4567;
vint16m4_t i16m4_col0123 = __riscv_vlmul_ext_v_i16m1_i16m4(col0);
i16m4_col0123 = __riscv_vslideup_vx_i16m4(i16m4_col0123, __riscv_vlmul_ext_v_i16m1_i16m4(col1), 8, 16);
i16m4_col0123 = __riscv_vslideup_vx_i16m4(i16m4_col0123, __riscv_vlmul_ext_v_i16m1_i16m4(col2), 16, 24);
i16m4_col0123 = __riscv_vslideup_vx_i16m4(i16m4_col0123, __riscv_vlmul_ext_v_i16m1_i16m4(col3), 24, 32);
tmp_i8m2 = __riscv_vnclip_wx_i8m2(i16m4_col0123, PASS1_BITS + 3, 32); // clamp -128 ~ 127
u8m2_col0123 = __riscv_vreinterpret_v_i8m2_u8m2(tmp_i8m2);
u8m2_col0123 = __riscv_vadd_vx_u8m2(u8m2_col0123, CENTERJSAMPLE, 32); // clamp 0 ~ 255

vint16m4_t i16m4_col4567 = __riscv_vlmul_ext_v_i16m1_i16m4(col4);
i16m4_col4567 = __riscv_vslideup_vx_i16m4(i16m4_col4567, __riscv_vlmul_ext_v_i16m1_i16m4(col5), 8, 16);
i16m4_col4567 = __riscv_vslideup_vx_i16m4(i16m4_col4567, __riscv_vlmul_ext_v_i16m1_i16m4(col6), 16, 24);
i16m4_col4567 = __riscv_vslideup_vx_i16m4(i16m4_col4567, __riscv_vlmul_ext_v_i16m1_i16m4(col7), 24, 32);
tmp_i8m2 = __riscv_vnclip_wx_i8m2(i16m4_col4567, PASS1_BITS + 3, 32); // clamp -128 ~ 127
u8m2_col4567 = __riscv_vreinterpret_v_i8m2_u8m2(tmp_i8m2);
u8m2_col4567 = __riscv_vadd_vx_u8m2(u8m2_col4567, CENTERJSAMPLE, 32); // clamp 0 ~ 255

vuint8m4_t u8m4_col_all = __riscv_vlmul_ext_v_u8m2_u8m4(u8m2_col0123);
u8m4_col_all = __riscv_vslideup_vx_u8m4(u8m4_col_all, __riscv_vlmul_ext_v_u8m2_u8m4(u8m2_col4567), 32, 64);

/* Transpose block to prepare for store. */
vuint8m4_t u8m4_trans_all = __riscv_vrgather_vv_u8m4(u8m4_col_all, vg_reg8, DCTSIZE2);

// extract columns
vuint8mf2_t u8mf2_col_0, u8mf2_col_1, u8mf2_col_2, u8mf2_col_3;
vuint8mf2_t u8mf2_col_4, u8mf2_col_5, u8mf2_col_6, u8mf2_col_7;

vuint8m4_t slidedown_m4 = __riscv_vslidedown_vx_u8m4(u8m4_trans_all, 0, vl);
u8mf2_col_0 = __riscv_vlmul_trunc_v_u8m4_u8mf2(slidedown_m4);

slidedown_m4 = __riscv_vslidedown_vx_u8m4(u8m4_trans_all, 8, vl);
u8mf2_col_1 = __riscv_vlmul_trunc_v_u8m4_u8mf2(slidedown_m4);

slidedown_m4 = __riscv_vslidedown_vx_u8m4(u8m4_trans_all, 16, vl);
u8mf2_col_2 = __riscv_vlmul_trunc_v_u8m4_u8mf2(slidedown_m4);

slidedown_m4 = __riscv_vslidedown_vx_u8m4(u8m4_trans_all, 24, vl);
u8mf2_col_3 = __riscv_vlmul_trunc_v_u8m4_u8mf2(slidedown_m4);

slidedown_m4 = __riscv_vslidedown_vx_u8m4(u8m4_trans_all, 32, vl);
u8mf2_col_4 = __riscv_vlmul_trunc_v_u8m4_u8mf2(slidedown_m4);

slidedown_m4 = __riscv_vslidedown_vx_u8m4(u8m4_trans_all, 40, vl);
u8mf2_col_5 = __riscv_vlmul_trunc_v_u8m4_u8mf2(slidedown_m4);

slidedown_m4 = __riscv_vslidedown_vx_u8m4(u8m4_trans_all, 48, vl);
u8mf2_col_6 = __riscv_vlmul_trunc_v_u8m4_u8mf2(slidedown_m4);

slidedown_m4 = __riscv_vslidedown_vx_u8m4(u8m4_trans_all, 56, vl);
u8mf2_col_7 = __riscv_vlmul_trunc_v_u8m4_u8mf2(slidedown_m4);

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;
JSAMPROW outptr4 = output_buf[4] + output_col;
JSAMPROW outptr5 = output_buf[5] + output_col;
JSAMPROW outptr6 = output_buf[6] + output_col;
JSAMPROW outptr7 = output_buf[7] + output_col;

/* Store DCT block to memory. */
__riscv_vse8_v_u8mf2(outptr0, u8mf2_col_0, vl);
__riscv_vse8_v_u8mf2(outptr1, u8mf2_col_1, vl);
__riscv_vse8_v_u8mf2(outptr2, u8mf2_col_2, vl);
__riscv_vse8_v_u8mf2(outptr3, u8mf2_col_3, vl);
__riscv_vse8_v_u8mf2(outptr4, u8mf2_col_4, vl);
__riscv_vse8_v_u8mf2(outptr5, u8mf2_col_5, vl);
__riscv_vse8_v_u8mf2(outptr6, u8mf2_col_6, vl);
__riscv_vse8_v_u8mf2(outptr7, u8mf2_col_7, vl);
}

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