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/*
* jquanti-neon.c - sample conversion and integer quantization (Arm NEON)
*
* Copyright 2020 The Chromium Authors. All Rights Reserved.
*
* This software is provided 'as-is', without any express or implied
* warranty. In no event will the authors be held liable for any damages
* arising from the use of this software.
*
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
*
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/
#define JPEG_INTERNALS
#include "../../../jinclude.h"
#include "../../../jpeglib.h"
#include "../../../jsimd.h"
#include "../../../jdct.h"
#include "../../../jsimddct.h"
#include "../../jsimd.h"
#include <arm_neon.h>
/*
* Pixel channel sample values have range [0,255]. The Discrete Cosine
* Transform (DCT) operates on values centered around 0.
*
* To prepare sample values for the DCT, load samples into a DCT workspace,
* subtracting CENTREJSAMPLE (128). The samples, now in range [-128, 127],
* are also widened from 8- to 16-bit.
*
* The equivalent scalar C function 'convsamp' can be found in jcdctmgr.c.
*/
void jsimd_convsamp_neon(JSAMPARRAY sample_data,
JDIMENSION start_col,
DCTELEM *workspace)
{
uint8x8_t samp_row0 = vld1_u8(sample_data[0] + start_col);
uint8x8_t samp_row1 = vld1_u8(sample_data[1] + start_col);
uint8x8_t samp_row2 = vld1_u8(sample_data[2] + start_col);
uint8x8_t samp_row3 = vld1_u8(sample_data[3] + start_col);
uint8x8_t samp_row4 = vld1_u8(sample_data[4] + start_col);
uint8x8_t samp_row5 = vld1_u8(sample_data[5] + start_col);
uint8x8_t samp_row6 = vld1_u8(sample_data[6] + start_col);
uint8x8_t samp_row7 = vld1_u8(sample_data[7] + start_col);
int16x8_t row0 = vreinterpretq_s16_u16(vsubl_u8(samp_row0,
vdup_n_u8(CENTERJSAMPLE)));
int16x8_t row1 = vreinterpretq_s16_u16(vsubl_u8(samp_row1,
vdup_n_u8(CENTERJSAMPLE)));
int16x8_t row2 = vreinterpretq_s16_u16(vsubl_u8(samp_row2,
vdup_n_u8(CENTERJSAMPLE)));
int16x8_t row3 = vreinterpretq_s16_u16(vsubl_u8(samp_row3,
vdup_n_u8(CENTERJSAMPLE)));
int16x8_t row4 = vreinterpretq_s16_u16(vsubl_u8(samp_row4,
vdup_n_u8(CENTERJSAMPLE)));
int16x8_t row5 = vreinterpretq_s16_u16(vsubl_u8(samp_row5,
vdup_n_u8(CENTERJSAMPLE)));
int16x8_t row6 = vreinterpretq_s16_u16(vsubl_u8(samp_row6,
vdup_n_u8(CENTERJSAMPLE)));
int16x8_t row7 = vreinterpretq_s16_u16(vsubl_u8(samp_row7,
vdup_n_u8(CENTERJSAMPLE)));
vst1q_s16(workspace + 0 * DCTSIZE, row0);
vst1q_s16(workspace + 1 * DCTSIZE, row1);
vst1q_s16(workspace + 2 * DCTSIZE, row2);
vst1q_s16(workspace + 3 * DCTSIZE, row3);
vst1q_s16(workspace + 4 * DCTSIZE, row4);
vst1q_s16(workspace + 5 * DCTSIZE, row5);
vst1q_s16(workspace + 6 * DCTSIZE, row6);
vst1q_s16(workspace + 7 * DCTSIZE, row7);
}
/*
* After the DCT, the resulting coefficient values need to be divided by a
* quantization value.
*
* To avoid a slow division operation, the DCT coefficients are multiplied by
* the (scaled) reciprocal of the quantization values and then right-shifted.
*
* The equivalent scalar C function 'quantize' can be found in jcdctmgr.c.
*/
void jsimd_quantize_neon(JCOEFPTR coef_block,
DCTELEM *divisors,
DCTELEM *workspace)
{
JCOEFPTR out_ptr = coef_block;
UDCTELEM *recip_ptr = (UDCTELEM *)divisors;
UDCTELEM *corr_ptr = (UDCTELEM *)divisors + DCTSIZE2;
DCTELEM *shift_ptr = divisors + 3 * DCTSIZE2;
for (int i = 0; i < DCTSIZE; i += DCTSIZE / 2) {
/* Load DCT coefficients. */
int16x8_t row0 = vld1q_s16(workspace + (i + 0) * DCTSIZE);
int16x8_t row1 = vld1q_s16(workspace + (i + 1) * DCTSIZE);
int16x8_t row2 = vld1q_s16(workspace + (i + 2) * DCTSIZE);
int16x8_t row3 = vld1q_s16(workspace + (i + 3) * DCTSIZE);
/* Load reciprocals of quantization values. */
uint16x8_t recip0 = vld1q_u16(recip_ptr + (i + 0) * DCTSIZE);
uint16x8_t recip1 = vld1q_u16(recip_ptr + (i + 1) * DCTSIZE);
uint16x8_t recip2 = vld1q_u16(recip_ptr + (i + 2) * DCTSIZE);
uint16x8_t recip3 = vld1q_u16(recip_ptr + (i + 3) * DCTSIZE);
uint16x8_t corr0 = vld1q_u16(corr_ptr + (i + 0) * DCTSIZE);
uint16x8_t corr1 = vld1q_u16(corr_ptr + (i + 1) * DCTSIZE);
uint16x8_t corr2 = vld1q_u16(corr_ptr + (i + 2) * DCTSIZE);
uint16x8_t corr3 = vld1q_u16(corr_ptr + (i + 3) * DCTSIZE);
int16x8_t shift0 = vld1q_s16(shift_ptr + (i + 0) * DCTSIZE);
int16x8_t shift1 = vld1q_s16(shift_ptr + (i + 1) * DCTSIZE);
int16x8_t shift2 = vld1q_s16(shift_ptr + (i + 2) * DCTSIZE);
int16x8_t shift3 = vld1q_s16(shift_ptr + (i + 3) * DCTSIZE);
/* Extract sign from coefficients. */
int16x8_t sign_row0 = vshrq_n_s16(row0, 15);
int16x8_t sign_row1 = vshrq_n_s16(row1, 15);
int16x8_t sign_row2 = vshrq_n_s16(row2, 15);
int16x8_t sign_row3 = vshrq_n_s16(row3, 15);
/* Get absolute value of DCT coefficients. */
uint16x8_t abs_row0 = vreinterpretq_u16_s16(vabsq_s16(row0));
uint16x8_t abs_row1 = vreinterpretq_u16_s16(vabsq_s16(row1));
uint16x8_t abs_row2 = vreinterpretq_u16_s16(vabsq_s16(row2));
uint16x8_t abs_row3 = vreinterpretq_u16_s16(vabsq_s16(row3));
/* Add correction. */
abs_row0 = vaddq_u16(abs_row0, corr0);
abs_row1 = vaddq_u16(abs_row1, corr1);
abs_row2 = vaddq_u16(abs_row2, corr2);
abs_row3 = vaddq_u16(abs_row3, corr3);
/* Multiply DCT coefficients by quantization reciprocal. */
int32x4_t row0_l = vreinterpretq_s32_u32(vmull_u16(vget_low_u16(abs_row0),
vget_low_u16(recip0)));
int32x4_t row0_h = vreinterpretq_s32_u32(vmull_u16(vget_high_u16(abs_row0),
vget_high_u16(recip0)));
int32x4_t row1_l = vreinterpretq_s32_u32(vmull_u16(vget_low_u16(abs_row1),
vget_low_u16(recip1)));
int32x4_t row1_h = vreinterpretq_s32_u32(vmull_u16(vget_high_u16(abs_row1),
vget_high_u16(recip1)));
int32x4_t row2_l = vreinterpretq_s32_u32(vmull_u16(vget_low_u16(abs_row2),
vget_low_u16(recip2)));
int32x4_t row2_h = vreinterpretq_s32_u32(vmull_u16(vget_high_u16(abs_row2),
vget_high_u16(recip2)));
int32x4_t row3_l = vreinterpretq_s32_u32(vmull_u16(vget_low_u16(abs_row3),
vget_low_u16(recip3)));
int32x4_t row3_h = vreinterpretq_s32_u32(vmull_u16(vget_high_u16(abs_row3),
vget_high_u16(recip3)));
/* Narrow back to 16-bit. */
row0 = vcombine_s16(vshrn_n_s32(row0_l, 16), vshrn_n_s32(row0_h, 16));
row1 = vcombine_s16(vshrn_n_s32(row1_l, 16), vshrn_n_s32(row1_h, 16));
row2 = vcombine_s16(vshrn_n_s32(row2_l, 16), vshrn_n_s32(row2_h, 16));
row3 = vcombine_s16(vshrn_n_s32(row3_l, 16), vshrn_n_s32(row3_h, 16));
/* Since VSHR only supports an immediate as its second argument, negate */
/* the shift value and shift left. */
row0 = vreinterpretq_s16_u16(vshlq_u16(vreinterpretq_u16_s16(row0),
vnegq_s16(shift0)));
row1 = vreinterpretq_s16_u16(vshlq_u16(vreinterpretq_u16_s16(row1),
vnegq_s16(shift1)));
row2 = vreinterpretq_s16_u16(vshlq_u16(vreinterpretq_u16_s16(row2),
vnegq_s16(shift2)));
row3 = vreinterpretq_s16_u16(vshlq_u16(vreinterpretq_u16_s16(row3),
vnegq_s16(shift3)));
/* Restore sign to original product. */
row0 = veorq_s16(row0, sign_row0);
row0 = vsubq_s16(row0, sign_row0);
row1 = veorq_s16(row1, sign_row1);
row1 = vsubq_s16(row1, sign_row1);
row2 = veorq_s16(row2, sign_row2);
row2 = vsubq_s16(row2, sign_row2);
row3 = veorq_s16(row3, sign_row3);
row3 = vsubq_s16(row3, sign_row3);
/* Store quantized coefficients to memory. */
vst1q_s16(out_ptr + (i + 0) * DCTSIZE, row0);
vst1q_s16(out_ptr + (i + 1) * DCTSIZE, row1);
vst1q_s16(out_ptr + (i + 2) * DCTSIZE, row2);
vst1q_s16(out_ptr + (i + 3) * DCTSIZE, row3);
}
}
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