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
10 #include <arm_neon.h>
11
12 #include <xnnpack/math-stubs.h>
13
14
xnn_math_f32_qu8_cvt__neon(size_t n,const float * input,uint8_t * output,uint8_t output_zero_point)15 void xnn_math_f32_qu8_cvt__neon(
16 size_t n,
17 const float* input,
18 uint8_t* output,
19 uint8_t output_zero_point)
20 {
21 assert(n % (8 * sizeof(uint8_t)) == 0);
22
23 const float32x4_t vfmagic = vdupq_n_f32(12582912.0f);
24 const int32x4_t vimagic = vdupq_n_s32(INT32_C(0x4B400000) - (int32_t) output_zero_point);
25 for (; n != 0; n -= 8 * sizeof(uint8_t)) {
26 float32x4_t vx_lo = vld1q_f32(input); input += 4;
27 float32x4_t vx_hi = vld1q_f32(input); input += 4;
28
29 vx_lo = vaddq_f32(vx_lo, vfmagic);
30 vx_hi = vaddq_f32(vx_hi, vfmagic);
31
32 int32x4_t vy_lo = vreinterpretq_s32_f32(vx_lo);
33 int32x4_t vy_hi = vreinterpretq_s32_f32(vx_hi);
34
35 vy_lo = vqsubq_s32(vy_lo, vimagic);
36 vy_hi = vqsubq_s32(vy_hi, vimagic);
37
38 const int16x8_t vy = vcombine_s16(vqmovn_s32(vy_lo), vqmovn_s32(vy_hi));
39
40 const uint8x8_t vout = vqmovun_s16(vy);
41 vst1_u8(output, vout); output += 8;
42 }
43 }
44