1 // Copyright 2018 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
4
5 #include "go_asm.h"
6 #include "textflag.h"
7
8 TEXT ·Count(SB),NOSPLIT,$0-40
9 MOVD b_base+0(FP), R0
10 MOVD b_len+8(FP), R2
11 MOVBU c+24(FP), R1
12 MOVD $ret+32(FP), R8
13 B countbytebody<>(SB)
14
15 TEXT ·CountString(SB),NOSPLIT,$0-32
16 MOVD s_base+0(FP), R0
17 MOVD s_len+8(FP), R2
18 MOVBU c+16(FP), R1
19 MOVD $ret+24(FP), R8
20 B countbytebody<>(SB)
21
22 // input:
23 // R0: data
24 // R2: data len
25 // R1: byte to find
26 // R8: address to put result
27 TEXT countbytebody<>(SB),NOSPLIT,$0
28 // R11 = count of byte to search
29 MOVD $0, R11
30 // short path to handle 0-byte case
31 CBZ R2, done
32 CMP $0x20, R2
33 // jump directly to tail if length < 32
34 BLO tail
35 ANDS $0x1f, R0, R9
36 BEQ chunk
37 // Work with not 32-byte aligned head
38 BIC $0x1f, R0, R3
39 ADD $0x20, R3
40 head_loop:
41 MOVBU.P 1(R0), R5
42 CMP R5, R1
43 CINC EQ, R11, R11
44 SUB $1, R2, R2
45 CMP R0, R3
46 BNE head_loop
47 // Work with 32-byte aligned chunks
48 chunk:
49 BIC $0x1f, R2, R9
50 // The first chunk can also be the last
51 CBZ R9, tail
52 // R3 = end of 32-byte chunks
53 ADD R0, R9, R3
54 MOVD $1, R5
55 VMOV R5, V5.B16
56 // R2 = length of tail
57 SUB R9, R2, R2
58 // Duplicate R1 (byte to search) to 16 1-byte elements of V0
59 VMOV R1, V0.B16
60 // Clear the low 64-bit element of V7 and V8
61 VEOR V7.B8, V7.B8, V7.B8
62 VEOR V8.B8, V8.B8, V8.B8
63 // Count the target byte in 32-byte chunk
64 chunk_loop:
65 VLD1.P (R0), [V1.B16, V2.B16]
66 CMP R0, R3
67 VCMEQ V0.B16, V1.B16, V3.B16
68 VCMEQ V0.B16, V2.B16, V4.B16
69 // Clear the higher 7 bits
70 VAND V5.B16, V3.B16, V3.B16
71 VAND V5.B16, V4.B16, V4.B16
72 // Count lanes match the requested byte
73 VADDP V4.B16, V3.B16, V6.B16 // 32B->16B
74 VUADDLV V6.B16, V7
75 // Accumulate the count in low 64-bit element of V8 when inside the loop
76 VADD V7, V8
77 BNE chunk_loop
78 VMOV V8.D[0], R6
79 ADD R6, R11, R11
80 CBZ R2, done
81 tail:
82 // Work with tail shorter than 32 bytes
83 MOVBU.P 1(R0), R5
84 SUB $1, R2, R2
85 CMP R5, R1
86 CINC EQ, R11, R11
87 CBNZ R2, tail
88 done:
89 MOVD R11, (R8)
90 RET
91
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