1 // Copyright 2021 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 #include <assert.h> 7 #include <stddef.h> 8 #include <stdint.h> 9 #include <math.h> 10 11 #include <xnnpack/math.h> 12 #include <xnnpack/math-stubs.h> 13 14 #include <fp16/bitcasts.h> 15 16 xnn_math_f32_f16_cvt__scalar_fabsf(size_t n,const float * input,void * output)17void xnn_math_f32_f16_cvt__scalar_fabsf( 18 size_t n, 19 const float* input, 20 void* output) 21 { 22 assert(n % (sizeof(uint16_t)) == 0); 23 24 const float vscale_to_inf = 0x1.0p+112f; 25 const uint32_t vexp_bias = UINT32_C(0x07800000); 26 const float vscale_to_zero = 0x1.0p-110f; 27 const uint32_t vexpw_max = UINT32_C(0x7F800000); 28 const uint32_t vbias_min = UINT32_C(0x40000000); 29 const uint16_t vexph_mask = UINT16_C(0x7C00); 30 const uint16_t vmanth_mask = UINT16_C(0x0FFF); 31 const uint16_t vnanh = UINT16_C(0x7E00); 32 33 uint16_t* o = (uint16_t*) output; 34 for (; n != 0; n -= sizeof(uint16_t)) { 35 const float vx = *input++; 36 37 const float vabsx = fabsf(vx); 38 uint32_t vsignw = fp32_to_bits(vx); 39 40 const uint32_t vnonsignw = fp32_to_bits(vabsx); 41 float vf = vabsx * vscale_to_inf; 42 43 uint32_t vbias = vnonsignw + vexp_bias; 44 vsignw ^= vnonsignw; 45 46 vf *= vscale_to_zero; 47 vbias &= vexpw_max; 48 49 vbias = math_max_u32(vbias, vbias_min); 50 51 vf += fp32_from_bits(vbias); 52 53 const uint32_t vbits = fp32_to_bits(vf); 54 55 const uint16_t vexph = (uint16_t) (vbits >> 13) & vexph_mask; 56 const uint16_t vmanth = (uint16_t) vbits & vmanth_mask; 57 const uint16_t vsignh = (uint16_t) (vsignw >> 16); 58 59 uint16_t vh = vexph + vmanth; 60 if XNN_UNPREDICTABLE(vnonsignw > vexpw_max) { 61 vh = vnanh; 62 } 63 vh |= vsignh; 64 65 *o++ = vh; 66 } 67 } 68