1// Copyright 2022 Google LLC 2// 3// This source code is licensed under the BSD-style license found in the 4// LICENSE file in the root directory of this source tree. 5 6$assert BATCH_TILE >= 1 7#include <assert.h> 8#include <stddef.h> 9#include <stdint.h> 10 11#include <xnnpack/math.h> 12#include <xnnpack/vlog.h> 13 14extern XNN_INTERNAL const uint16_t xnn_table_vlog[129]; 15 16#define LOG_SEGMENTS_LOG2 7 17#define LOG_SCALE 65536 18#define LOG_SCALE_LOG2 16 19#define LOG_COEFF 45426 20 21static uint32_t xnn_u32_log32(uint32_t x, uint32_t out_scale) { 22 const uint32_t log2x = math_clz_nonzero_u32(x) ^ 31; 23 int32_t frac = x - (UINT32_C(1) << log2x); 24 frac <<= math_doz_u32(LOG_SCALE_LOG2, log2x); 25 frac >>= math_doz_u32(log2x, LOG_SCALE_LOG2); 26 27 const uint32_t base_seg = frac >> (LOG_SCALE_LOG2 - LOG_SEGMENTS_LOG2); 28 const uint32_t seg_unit = (UINT32_C(1) << LOG_SCALE_LOG2) >> LOG_SEGMENTS_LOG2; 29 30 const int32_t c0 = xnn_table_vlog[base_seg]; 31 const int32_t c1 = xnn_table_vlog[base_seg + 1]; 32 const int32_t seg_base = seg_unit * base_seg; 33 const int32_t rel_pos = math_asr_s32((c1 - c0) * (frac - seg_base), LOG_SCALE_LOG2); 34 const uint32_t fraction = frac + c0 + rel_pos; 35 const uint32_t log2 = (log2x << LOG_SCALE_LOG2) + fraction; 36 const uint32_t round = LOG_SCALE >> 1; 37 const uint32_t loge = (math_mulext_u32(log2, LOG_COEFF) + round) >> LOG_SCALE_LOG2; 38 39 const uint32_t loge_scaled = (out_scale * loge + round) >> LOG_SCALE_LOG2; 40 return loge_scaled; 41} 42 43void xnn_u32_vlog_ukernel__scalar_x${BATCH_TILE}( 44 size_t batch, 45 const uint32_t* input, 46 uint32_t input_lshift, 47 uint32_t output_scale, 48 uint16_t* output) { 49 50 assert(batch != 0); 51 assert(input != NULL); 52 assert(input_lshift < 32); 53 assert(output != NULL); 54 55 $if BATCH_TILE > 1: 56 for (; batch >= ${BATCH_TILE}; batch -= ${BATCH_TILE}) { 57 $for N in range(BATCH_TILE): 58 const uint32_t vi${N} = input[${N}]; 59 input += ${BATCH_TILE}; 60 61 $for N in range(BATCH_TILE): 62 const uint32_t scaled${N} = vi${N} << input_lshift; 63 64 $for N in range(BATCH_TILE): 65 const uint32_t log_value${N} = XNN_LIKELY(scaled${N} != 0) ? xnn_u32_log32(scaled${N}, output_scale) : 0; 66 67 const uint32_t vout${N} = math_min_u32(log_value${N}, (uint32_t) INT16_MAX); // signed max value 68 output[${N}] = (uint16_t) vout${N}; 69 70 output += ${BATCH_TILE}; 71 } 72 73 if XNN_UNLIKELY(batch != 0) { 74 do { 75 const uint32_t vi = *input++; 76 const uint32_t scaled = vi << input_lshift; 77 78 const uint32_t log_value = XNN_LIKELY(scaled != 0) ? xnn_u32_log32(scaled, output_scale) : 0; 79 80 const uint32_t vout = math_min_u32(log_value, (uint32_t) INT16_MAX); 81 *output++ = (uint16_t) vout; 82 } while (--batch != 0); 83 } 84} 85