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// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build (ppc64 || ppc64le) && !purego
#include "textflag.h"
// func xorBytes(dst, a, b *byte, n int)
TEXT ·xorBytes(SB), NOSPLIT, $0
MOVD dst+0(FP), R3 // R3 = dst
MOVD a+8(FP), R4 // R4 = a
MOVD b+16(FP), R5 // R5 = b
MOVD n+24(FP), R6 // R6 = n
CMPU R6, $32, CR7 // Check if n ≥ 32 bytes
MOVD R0, R8 // R8 = index
CMPU R6, $8, CR6 // Check if 8 ≤ n < 32 bytes
BLT CR6, small // Smaller than 8
BLT CR7, xor16 // Case for 16 ≤ n < 32 bytes
// Case for n ≥ 32 bytes
preloop32:
SRD $5, R6, R7 // Setup loop counter
MOVD R7, CTR
MOVD $16, R10
ANDCC $31, R6, R9 // Check for tailing bytes for later
loop32:
LXVD2X (R4)(R8), VS32 // VS32 = a[i,...,i+15]
LXVD2X (R4)(R10), VS34
LXVD2X (R5)(R8), VS33 // VS33 = b[i,...,i+15]
LXVD2X (R5)(R10), VS35
XXLXOR VS32, VS33, VS32 // VS34 = a[] ^ b[]
XXLXOR VS34, VS35, VS34
STXVD2X VS32, (R3)(R8) // Store to dst
STXVD2X VS34, (R3)(R10)
ADD $32, R8 // Update index
ADD $32, R10
BC 16, 0, loop32 // bdnz loop16
BEQ CR0, done
MOVD R9, R6
CMP R6, $8
BLT small
xor16:
CMP R6, $16
BLT xor8
LXVD2X (R4)(R8), VS32
LXVD2X (R5)(R8), VS33
XXLXOR VS32, VS33, VS32
STXVD2X VS32, (R3)(R8)
ADD $16, R8
ADD $-16, R6
CMP R6, $8
BLT small
xor8:
// Case for 8 ≤ n < 16 bytes
MOVD (R4)(R8), R14 // R14 = a[i,...,i+7]
MOVD (R5)(R8), R15 // R15 = b[i,...,i+7]
XOR R14, R15, R16 // R16 = a[] ^ b[]
SUB $8, R6 // n = n - 8
MOVD R16, (R3)(R8) // Store to dst
ADD $8, R8
// Check if we're finished
CMP R6, R0
BGT small
RET
// Case for n < 8 bytes and tailing bytes from the
// previous cases.
small:
CMP R6, R0
BEQ done
MOVD R6, CTR // Setup loop counter
loop:
MOVBZ (R4)(R8), R14 // R14 = a[i]
MOVBZ (R5)(R8), R15 // R15 = b[i]
XOR R14, R15, R16 // R16 = a[i] ^ b[i]
MOVB R16, (R3)(R8) // Store to dst
ADD $1, R8
BC 16, 0, loop // bdnz loop
done:
RET
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