/* * jquanti-neon.c - sample data conversion and quantization (Arm Neon) * * Copyright (C) 2020-2021, 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 /* After downsampling, the resulting sample values are in the range [0, 255], * but 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 CENTERJSAMPLE (128). The samples, now in the 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 array of coefficient values needs to be divided * by an array of quantization values. * * To avoid a slow division operation, the DCT coefficients are multiplied by * the (scaled) reciprocals 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; int i; #if defined(__clang__) && (defined(__aarch64__) || defined(_M_ARM64)) #pragma unroll #endif for (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 reciprocals. */ 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); } }