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/*
* jchuff-neon.c - Huffman entropy encoding (32-bit 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.
*
* NOTE: All referenced figures are from
* Recommendation ITU-T T.81 (1992) | ISO/IEC 10918-1:1994.
*/
#define JPEG_INTERNALS
#include "../../../jinclude.h"
#include "../../../jpeglib.h"
#include "../../../jsimd.h"
#include "../../../jdct.h"
#include "../../../jsimddct.h"
#include "../../jsimd.h"
#include "../jchuff.h"
#include "neon-compat.h"
#include <limits.h>
#include <arm_neon.h>
JOCTET *jsimd_huff_encode_one_block_neon(void *state, JOCTET *buffer,
JCOEFPTR block, int last_dc_val,
c_derived_tbl *dctbl,
c_derived_tbl *actbl)
{
uint8_t block_nbits[DCTSIZE2];
uint16_t block_diff[DCTSIZE2];
/* Load rows of coefficients from DCT block in zig-zag order. */
/* Compute DC coefficient difference value. (F.1.1.5.1) */
int16x8_t row0 = vdupq_n_s16(block[0] - last_dc_val);
row0 = vld1q_lane_s16(block + 1, row0, 1);
row0 = vld1q_lane_s16(block + 8, row0, 2);
row0 = vld1q_lane_s16(block + 16, row0, 3);
row0 = vld1q_lane_s16(block + 9, row0, 4);
row0 = vld1q_lane_s16(block + 2, row0, 5);
row0 = vld1q_lane_s16(block + 3, row0, 6);
row0 = vld1q_lane_s16(block + 10, row0, 7);
int16x8_t row1 = vld1q_dup_s16(block + 17);
row1 = vld1q_lane_s16(block + 24, row1, 1);
row1 = vld1q_lane_s16(block + 32, row1, 2);
row1 = vld1q_lane_s16(block + 25, row1, 3);
row1 = vld1q_lane_s16(block + 18, row1, 4);
row1 = vld1q_lane_s16(block + 11, row1, 5);
row1 = vld1q_lane_s16(block + 4, row1, 6);
row1 = vld1q_lane_s16(block + 5, row1, 7);
int16x8_t row2 = vld1q_dup_s16(block + 12);
row2 = vld1q_lane_s16(block + 19, row2, 1);
row2 = vld1q_lane_s16(block + 26, row2, 2);
row2 = vld1q_lane_s16(block + 33, row2, 3);
row2 = vld1q_lane_s16(block + 40, row2, 4);
row2 = vld1q_lane_s16(block + 48, row2, 5);
row2 = vld1q_lane_s16(block + 41, row2, 6);
row2 = vld1q_lane_s16(block + 34, row2, 7);
int16x8_t row3 = vld1q_dup_s16(block + 27);
row3 = vld1q_lane_s16(block + 20, row3, 1);
row3 = vld1q_lane_s16(block + 13, row3, 2);
row3 = vld1q_lane_s16(block + 6, row3, 3);
row3 = vld1q_lane_s16(block + 7, row3, 4);
row3 = vld1q_lane_s16(block + 14, row3, 5);
row3 = vld1q_lane_s16(block + 21, row3, 6);
row3 = vld1q_lane_s16(block + 28, row3, 7);
int16x8_t abs_row0 = vabsq_s16(row0);
int16x8_t abs_row1 = vabsq_s16(row1);
int16x8_t abs_row2 = vabsq_s16(row2);
int16x8_t abs_row3 = vabsq_s16(row3);
int16x8_t row0_lz = vclzq_s16(abs_row0);
int16x8_t row1_lz = vclzq_s16(abs_row1);
int16x8_t row2_lz = vclzq_s16(abs_row2);
int16x8_t row3_lz = vclzq_s16(abs_row3);
/* Compute number of bits required to represent each coefficient. */
uint8x8_t row0_nbits = vsub_u8(vdup_n_u8(16),
vmovn_u16(vreinterpretq_u16_s16(row0_lz)));
uint8x8_t row1_nbits = vsub_u8(vdup_n_u8(16),
vmovn_u16(vreinterpretq_u16_s16(row1_lz)));
uint8x8_t row2_nbits = vsub_u8(vdup_n_u8(16),
vmovn_u16(vreinterpretq_u16_s16(row2_lz)));
uint8x8_t row3_nbits = vsub_u8(vdup_n_u8(16),
vmovn_u16(vreinterpretq_u16_s16(row3_lz)));
vst1_u8(block_nbits + 0 * DCTSIZE, row0_nbits);
vst1_u8(block_nbits + 1 * DCTSIZE, row1_nbits);
vst1_u8(block_nbits + 2 * DCTSIZE, row2_nbits);
vst1_u8(block_nbits + 3 * DCTSIZE, row3_nbits);
uint16x8_t row0_mask =
vshlq_u16(vreinterpretq_u16_s16(vshrq_n_s16(row0, 15)),
vnegq_s16(row0_lz));
uint16x8_t row1_mask =
vshlq_u16(vreinterpretq_u16_s16(vshrq_n_s16(row1, 15)),
vnegq_s16(row1_lz));
uint16x8_t row2_mask =
vshlq_u16(vreinterpretq_u16_s16(vshrq_n_s16(row2, 15)),
vnegq_s16(row2_lz));
uint16x8_t row3_mask =
vshlq_u16(vreinterpretq_u16_s16(vshrq_n_s16(row3, 15)),
vnegq_s16(row3_lz));
uint16x8_t row0_diff = veorq_u16(vreinterpretq_u16_s16(abs_row0), row0_mask);
uint16x8_t row1_diff = veorq_u16(vreinterpretq_u16_s16(abs_row1), row1_mask);
uint16x8_t row2_diff = veorq_u16(vreinterpretq_u16_s16(abs_row2), row2_mask);
uint16x8_t row3_diff = veorq_u16(vreinterpretq_u16_s16(abs_row3), row3_mask);
/* Store diff values for rows 0, 1, 2, and 3. */
vst1q_u16(block_diff + 0 * DCTSIZE, row0_diff);
vst1q_u16(block_diff + 1 * DCTSIZE, row1_diff);
vst1q_u16(block_diff + 2 * DCTSIZE, row2_diff);
vst1q_u16(block_diff + 3 * DCTSIZE, row3_diff);
/* Load last four rows of coefficients from DCT block in zig-zag order. */
int16x8_t row4 = vld1q_dup_s16(block + 35);
row4 = vld1q_lane_s16(block + 42, row4, 1);
row4 = vld1q_lane_s16(block + 49, row4, 2);
row4 = vld1q_lane_s16(block + 56, row4, 3);
row4 = vld1q_lane_s16(block + 57, row4, 4);
row4 = vld1q_lane_s16(block + 50, row4, 5);
row4 = vld1q_lane_s16(block + 43, row4, 6);
row4 = vld1q_lane_s16(block + 36, row4, 7);
int16x8_t row5 = vld1q_dup_s16(block + 29);
row5 = vld1q_lane_s16(block + 22, row5, 1);
row5 = vld1q_lane_s16(block + 15, row5, 2);
row5 = vld1q_lane_s16(block + 23, row5, 3);
row5 = vld1q_lane_s16(block + 30, row5, 4);
row5 = vld1q_lane_s16(block + 37, row5, 5);
row5 = vld1q_lane_s16(block + 44, row5, 6);
row5 = vld1q_lane_s16(block + 51, row5, 7);
int16x8_t row6 = vld1q_dup_s16(block + 58);
row6 = vld1q_lane_s16(block + 59, row6, 1);
row6 = vld1q_lane_s16(block + 52, row6, 2);
row6 = vld1q_lane_s16(block + 45, row6, 3);
row6 = vld1q_lane_s16(block + 38, row6, 4);
row6 = vld1q_lane_s16(block + 31, row6, 5);
row6 = vld1q_lane_s16(block + 39, row6, 6);
row6 = vld1q_lane_s16(block + 46, row6, 7);
int16x8_t row7 = vld1q_dup_s16(block + 53);
row7 = vld1q_lane_s16(block + 60, row7, 1);
row7 = vld1q_lane_s16(block + 61, row7, 2);
row7 = vld1q_lane_s16(block + 54, row7, 3);
row7 = vld1q_lane_s16(block + 47, row7, 4);
row7 = vld1q_lane_s16(block + 55, row7, 5);
row7 = vld1q_lane_s16(block + 62, row7, 6);
row7 = vld1q_lane_s16(block + 63, row7, 7);
int16x8_t abs_row4 = vabsq_s16(row4);
int16x8_t abs_row5 = vabsq_s16(row5);
int16x8_t abs_row6 = vabsq_s16(row6);
int16x8_t abs_row7 = vabsq_s16(row7);
int16x8_t row4_lz = vclzq_s16(abs_row4);
int16x8_t row5_lz = vclzq_s16(abs_row5);
int16x8_t row6_lz = vclzq_s16(abs_row6);
int16x8_t row7_lz = vclzq_s16(abs_row7);
/* Compute number of bits required to represent each coefficient. */
uint8x8_t row4_nbits = vsub_u8(vdup_n_u8(16),
vmovn_u16(vreinterpretq_u16_s16(row4_lz)));
uint8x8_t row5_nbits = vsub_u8(vdup_n_u8(16),
vmovn_u16(vreinterpretq_u16_s16(row5_lz)));
uint8x8_t row6_nbits = vsub_u8(vdup_n_u8(16),
vmovn_u16(vreinterpretq_u16_s16(row6_lz)));
uint8x8_t row7_nbits = vsub_u8(vdup_n_u8(16),
vmovn_u16(vreinterpretq_u16_s16(row7_lz)));
vst1_u8(block_nbits + 4 * DCTSIZE, row4_nbits);
vst1_u8(block_nbits + 5 * DCTSIZE, row5_nbits);
vst1_u8(block_nbits + 6 * DCTSIZE, row6_nbits);
vst1_u8(block_nbits + 7 * DCTSIZE, row7_nbits);
uint16x8_t row4_mask =
vshlq_u16(vreinterpretq_u16_s16(vshrq_n_s16(row4, 15)),
vnegq_s16(row4_lz));
uint16x8_t row5_mask =
vshlq_u16(vreinterpretq_u16_s16(vshrq_n_s16(row5, 15)),
vnegq_s16(row5_lz));
uint16x8_t row6_mask =
vshlq_u16(vreinterpretq_u16_s16(vshrq_n_s16(row6, 15)),
vnegq_s16(row6_lz));
uint16x8_t row7_mask =
vshlq_u16(vreinterpretq_u16_s16(vshrq_n_s16(row7, 15)),
vnegq_s16(row7_lz));
uint16x8_t row4_diff = veorq_u16(vreinterpretq_u16_s16(abs_row4), row4_mask);
uint16x8_t row5_diff = veorq_u16(vreinterpretq_u16_s16(abs_row5), row5_mask);
uint16x8_t row6_diff = veorq_u16(vreinterpretq_u16_s16(abs_row6), row6_mask);
uint16x8_t row7_diff = veorq_u16(vreinterpretq_u16_s16(abs_row7), row7_mask);
/* Store diff values for rows 4, 5, 6, and 7. */
vst1q_u16(block_diff + 4 * DCTSIZE, row4_diff);
vst1q_u16(block_diff + 5 * DCTSIZE, row5_diff);
vst1q_u16(block_diff + 6 * DCTSIZE, row6_diff);
vst1q_u16(block_diff + 7 * DCTSIZE, row7_diff);
/* Construct bitmap to accelerate encoding of AC coefficients. A set bit
* means that the corresponding coefficient != 0.
*/
uint8x8_t row0_nbits_gt0 = vcgt_u8(row0_nbits, vdup_n_u8(0));
uint8x8_t row1_nbits_gt0 = vcgt_u8(row1_nbits, vdup_n_u8(0));
uint8x8_t row2_nbits_gt0 = vcgt_u8(row2_nbits, vdup_n_u8(0));
uint8x8_t row3_nbits_gt0 = vcgt_u8(row3_nbits, vdup_n_u8(0));
uint8x8_t row4_nbits_gt0 = vcgt_u8(row4_nbits, vdup_n_u8(0));
uint8x8_t row5_nbits_gt0 = vcgt_u8(row5_nbits, vdup_n_u8(0));
uint8x8_t row6_nbits_gt0 = vcgt_u8(row6_nbits, vdup_n_u8(0));
uint8x8_t row7_nbits_gt0 = vcgt_u8(row7_nbits, vdup_n_u8(0));
/* { 0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01 } */
const uint8x8_t bitmap_mask =
vreinterpret_u8_u64(vmov_n_u64(0x0102040810204080));
row0_nbits_gt0 = vand_u8(row0_nbits_gt0, bitmap_mask);
row1_nbits_gt0 = vand_u8(row1_nbits_gt0, bitmap_mask);
row2_nbits_gt0 = vand_u8(row2_nbits_gt0, bitmap_mask);
row3_nbits_gt0 = vand_u8(row3_nbits_gt0, bitmap_mask);
row4_nbits_gt0 = vand_u8(row4_nbits_gt0, bitmap_mask);
row5_nbits_gt0 = vand_u8(row5_nbits_gt0, bitmap_mask);
row6_nbits_gt0 = vand_u8(row6_nbits_gt0, bitmap_mask);
row7_nbits_gt0 = vand_u8(row7_nbits_gt0, bitmap_mask);
uint8x8_t bitmap_rows_10 = vpadd_u8(row1_nbits_gt0, row0_nbits_gt0);
uint8x8_t bitmap_rows_32 = vpadd_u8(row3_nbits_gt0, row2_nbits_gt0);
uint8x8_t bitmap_rows_54 = vpadd_u8(row5_nbits_gt0, row4_nbits_gt0);
uint8x8_t bitmap_rows_76 = vpadd_u8(row7_nbits_gt0, row6_nbits_gt0);
uint8x8_t bitmap_rows_3210 = vpadd_u8(bitmap_rows_32, bitmap_rows_10);
uint8x8_t bitmap_rows_7654 = vpadd_u8(bitmap_rows_76, bitmap_rows_54);
uint8x8_t bitmap = vpadd_u8(bitmap_rows_7654, bitmap_rows_3210);
/* Shift left to remove DC bit. */
bitmap = vreinterpret_u8_u64(vshl_n_u64(vreinterpret_u64_u8(bitmap), 1));
/* Move bitmap to 32-bit scalar registers. */
uint32_t bitmap_1_32 = vget_lane_u32(vreinterpret_u32_u8(bitmap), 1);
uint32_t bitmap_33_63 = vget_lane_u32(vreinterpret_u32_u8(bitmap), 0);
/* Set up state and bit buffer for output bitstream. */
working_state *state_ptr = (working_state *)state;
int free_bits = state_ptr->cur.free_bits;
size_t put_buffer = state_ptr->cur.put_buffer;
/* Encode DC coefficient. */
unsigned int nbits = block_nbits[0];
/* Emit Huffman-coded symbol and additional diff bits. */
unsigned int diff = block_diff[0];
PUT_CODE(dctbl->ehufco[nbits], dctbl->ehufsi[nbits], diff)
/* Encode AC coefficients. */
unsigned int r = 0; /* r = run length of zeros */
unsigned int i = 1; /* i = number of coefficients encoded */
/* Code and size information for a run length of 16 zero coefficients */
const unsigned int code_0xf0 = actbl->ehufco[0xf0];
const unsigned int size_0xf0 = actbl->ehufsi[0xf0];
while (bitmap_1_32 != 0) {
r = BUILTIN_CLZ(bitmap_1_32);
i += r;
bitmap_1_32 <<= r;
nbits = block_nbits[i];
diff = block_diff[i];
while (r > 15) {
/* If run length > 15, emit special run-length-16 codes. */
PUT_BITS(code_0xf0, size_0xf0)
r -= 16;
}
/* Emit Huffman symbol for run length / number of bits. (F.1.2.2.1) */
unsigned int rs = (r << 4) + nbits;
PUT_CODE(actbl->ehufco[rs], actbl->ehufsi[rs], diff)
i++;
bitmap_1_32 <<= 1;
}
r = 33 - i;
i = 33;
while (bitmap_33_63 != 0) {
unsigned int leading_zeros = BUILTIN_CLZ(bitmap_33_63);
r += leading_zeros;
i += leading_zeros;
bitmap_33_63 <<= leading_zeros;
nbits = block_nbits[i];
diff = block_diff[i];
while (r > 15) {
/* If run length > 15, emit special run-length-16 codes. */
PUT_BITS(code_0xf0, size_0xf0)
r -= 16;
}
/* Emit Huffman symbol for run length / number of bits. (F.1.2.2.1) */
unsigned int rs = (r << 4) + nbits;
PUT_CODE(actbl->ehufco[rs], actbl->ehufsi[rs], diff)
r = 0;
i++;
bitmap_33_63 <<= 1;
}
/* If the last coefficient(s) were zero, emit an end-of-block (EOB) code.
* The value of RS for the EOB code is 0.
*/
if (i != 64) {
PUT_BITS(actbl->ehufco[0], actbl->ehufsi[0])
}
state_ptr->cur.put_buffer = put_buffer;
state_ptr->cur.free_bits = free_bits;
return buffer;
}