mirror of https://github.com/golang/go.git
63 lines
1.1 KiB
ArmAsm
63 lines
1.1 KiB
ArmAsm
// Copyright 2013 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build !nacl
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#include "textflag.h"
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// Registers
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#define Rdst R0
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#define Rsrc R1
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#define Rn R2
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#define Rstate R3
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#define Rpi R4
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#define Rpj R5
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#define Ri R6
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#define Rj R7
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#define Rk R8
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#define Rt R11
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#define Rt2 R12
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// func xorKeyStream(dst, src *byte, n int, state *[256]byte, i, j *uint8)
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TEXT ·xorKeyStream(SB),NOSPLIT,$0
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MOVW dst+0(FP), Rdst
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MOVW src+4(FP), Rsrc
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MOVW n+8(FP), Rn
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MOVW state+12(FP), Rstate
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MOVW pi+16(FP), Rpi
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MOVW pj+20(FP), Rpj
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MOVBU (Rpi), Ri
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MOVBU (Rpj), Rj
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MOVW $0, Rk
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loop:
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// i += 1; j += state[i]
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ADD $1, Ri
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AND $0xff, Ri
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MOVBU Ri<<2(Rstate), Rt
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ADD Rt, Rj
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AND $0xff, Rj
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// swap state[i] <-> state[j]
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MOVBU Rj<<2(Rstate), Rt2
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MOVB Rt2, Ri<<2(Rstate)
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MOVB Rt, Rj<<2(Rstate)
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// dst[k] = src[k] ^ state[state[i] + state[j]]
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ADD Rt2, Rt
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AND $0xff, Rt
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MOVBU Rt<<2(Rstate), Rt
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MOVBU Rk<<0(Rsrc), Rt2
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EOR Rt, Rt2
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MOVB Rt2, Rk<<0(Rdst)
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ADD $1, Rk
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CMP Rk, Rn
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BNE loop
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done:
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MOVB Ri, (Rpi)
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MOVB Rj, (Rpj)
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RET
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