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// Copyright 2014 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.
//
// ARM version of md5block.go
#include "textflag.h"
// SHA-1 block routine. See sha1block.go for Go equivalent.
//
// There are 80 rounds of 4 types:
// - rounds 0-15 are type 1 and load data (ROUND1 macro).
// - rounds 16-19 are type 1 and do not load data (ROUND1x macro).
// - rounds 20-39 are type 2 and do not load data (ROUND2 macro).
// - rounds 40-59 are type 3 and do not load data (ROUND3 macro).
// - rounds 60-79 are type 4 and do not load data (ROUND4 macro).
//
// Each round loads or shuffles the data, then computes a per-round
// function of b, c, d, and then mixes the result into and rotates the
// five registers a, b, c, d, e holding the intermediate results.
//
// The register rotation is implemented by rotating the arguments to
// the round macros instead of by explicit move instructions.
// Register definitions
#define Rdata R0 // Pointer to incoming data
#define Rconst R1 // Current constant for SHA round
#define Ra R2 // SHA-1 accumulator
#define Rb R3 // SHA-1 accumulator
#define Rc R4 // SHA-1 accumulator
#define Rd R5 // SHA-1 accumulator
#define Re R6 // SHA-1 accumulator
#define Rt0 R7 // Temporary
#define Rt1 R8 // Temporary
// r9, r10 are forbidden
// r11 is OK provided you check the assembler that no synthetic instructions use it
#define Rt2 R11 // Temporary
#define Rctr R12 // loop counter
#define Rw R14 // point to w buffer
// func block(dig *digest, p []byte)
// 0(FP) is *digest
// 4(FP) is p.array (struct Slice)
// 8(FP) is p.len
//12(FP) is p.cap
//
// Stack frame
#define p_end end-4(SP) // pointer to the end of data
#define p_data data-8(SP) // current data pointer (unused?)
#define w_buf buf-(8+4*80)(SP) //80 words temporary buffer w uint32[80]
#define saved abcde-(8+4*80+4*5)(SP) // saved sha1 registers a,b,c,d,e - these must be last (unused?)
// Total size +4 for saved LR is 352
// w[i] = p[j]<<24 | p[j+1]<<16 | p[j+2]<<8 | p[j+3]
// e += w[i]
#define LOAD(Re) \
MOVBU 2(Rdata), Rt0 ; \
MOVBU 3(Rdata), Rt1 ; \
MOVBU 1(Rdata), Rt2 ; \
ORR Rt0<<8, Rt1, Rt0 ; \
MOVBU.P 4(Rdata), Rt1 ; \
ORR Rt2<<16, Rt0, Rt0 ; \
ORR Rt1<<24, Rt0, Rt0 ; \
MOVW.P Rt0, 4(Rw) ; \
ADD Rt0, Re, Re
// tmp := w[(i-3)&0xf] ^ w[(i-8)&0xf] ^ w[(i-14)&0xf] ^ w[(i)&0xf]
// w[i&0xf] = tmp<<1 | tmp>>(32-1)
// e += w[i&0xf]
#define SHUFFLE(Re) \
MOVW (-16*4)(Rw), Rt0 ; \
MOVW (-14*4)(Rw), Rt1 ; \
MOVW (-8*4)(Rw), Rt2 ; \
EOR Rt0, Rt1, Rt0 ; \
MOVW (-3*4)(Rw), Rt1 ; \
EOR Rt2, Rt0, Rt0 ; \
EOR Rt0, Rt1, Rt0 ; \
MOVW Rt0@>(32-1), Rt0 ; \
MOVW.P Rt0, 4(Rw) ; \
ADD Rt0, Re, Re
// t1 = (b & c) | ((~b) & d)
#define FUNC1(Ra, Rb, Rc, Rd, Re) \
MVN Rb, Rt1 ; \
AND Rb, Rc, Rt0 ; \
AND Rd, Rt1, Rt1 ; \
ORR Rt0, Rt1, Rt1
// t1 = b ^ c ^ d
#define FUNC2(Ra, Rb, Rc, Rd, Re) \
EOR Rb, Rc, Rt1 ; \
EOR Rd, Rt1, Rt1
// t1 = (b & c) | (b & d) | (c & d) =
// t1 = (b & c) | ((b | c) & d)
#define FUNC3(Ra, Rb, Rc, Rd, Re) \
ORR Rb, Rc, Rt0 ; \
AND Rb, Rc, Rt1 ; \
AND Rd, Rt0, Rt0 ; \
ORR Rt0, Rt1, Rt1
#define FUNC4 FUNC2
// a5 := a<<5 | a>>(32-5)
// b = b<<30 | b>>(32-30)
// e = a5 + t1 + e + const
#define MIX(Ra, Rb, Rc, Rd, Re) \
ADD Rt1, Re, Re ; \
MOVW Rb@>(32-30), Rb ; \
ADD Ra@>(32-5), Re, Re ; \
ADD Rconst, Re, Re
#define ROUND1(Ra, Rb, Rc, Rd, Re) \
LOAD(Re) ; \
FUNC1(Ra, Rb, Rc, Rd, Re) ; \
MIX(Ra, Rb, Rc, Rd, Re)
#define ROUND1x(Ra, Rb, Rc, Rd, Re) \
SHUFFLE(Re) ; \
FUNC1(Ra, Rb, Rc, Rd, Re) ; \
MIX(Ra, Rb, Rc, Rd, Re)
#define ROUND2(Ra, Rb, Rc, Rd, Re) \
SHUFFLE(Re) ; \
FUNC2(Ra, Rb, Rc, Rd, Re) ; \
MIX(Ra, Rb, Rc, Rd, Re)
#define ROUND3(Ra, Rb, Rc, Rd, Re) \
SHUFFLE(Re) ; \
FUNC3(Ra, Rb, Rc, Rd, Re) ; \
MIX(Ra, Rb, Rc, Rd, Re)
#define ROUND4(Ra, Rb, Rc, Rd, Re) \
SHUFFLE(Re) ; \
FUNC4(Ra, Rb, Rc, Rd, Re) ; \
MIX(Ra, Rb, Rc, Rd, Re)
// func block(dig *digest, p []byte)
TEXT ·block(SB), 0, $352-16
MOVW p+4(FP), Rdata // pointer to the data
MOVW p_len+8(FP), Rt0 // number of bytes
ADD Rdata, Rt0
MOVW Rt0, p_end // pointer to end of data
// Load up initial SHA-1 accumulator
MOVW dig+0(FP), Rt0
MOVM.IA (Rt0), [Ra,Rb,Rc,Rd,Re]
loop:
// Save registers at SP+4 onwards
MOVM.IB [Ra,Rb,Rc,Rd,Re], (R13)
MOVW $w_buf, Rw
MOVW $0x5A827999, Rconst
MOVW $3, Rctr
loop1: ROUND1(Ra, Rb, Rc, Rd, Re)
ROUND1(Re, Ra, Rb, Rc, Rd)
ROUND1(Rd, Re, Ra, Rb, Rc)
ROUND1(Rc, Rd, Re, Ra, Rb)
ROUND1(Rb, Rc, Rd, Re, Ra)
SUB.S $1, Rctr
BNE loop1
ROUND1(Ra, Rb, Rc, Rd, Re)
ROUND1x(Re, Ra, Rb, Rc, Rd)
ROUND1x(Rd, Re, Ra, Rb, Rc)
ROUND1x(Rc, Rd, Re, Ra, Rb)
ROUND1x(Rb, Rc, Rd, Re, Ra)
MOVW $0x6ED9EBA1, Rconst
MOVW $4, Rctr
loop2: ROUND2(Ra, Rb, Rc, Rd, Re)
ROUND2(Re, Ra, Rb, Rc, Rd)
ROUND2(Rd, Re, Ra, Rb, Rc)
ROUND2(Rc, Rd, Re, Ra, Rb)
ROUND2(Rb, Rc, Rd, Re, Ra)
SUB.S $1, Rctr
BNE loop2
MOVW $0x8F1BBCDC, Rconst
MOVW $4, Rctr
loop3: ROUND3(Ra, Rb, Rc, Rd, Re)
ROUND3(Re, Ra, Rb, Rc, Rd)
ROUND3(Rd, Re, Ra, Rb, Rc)
ROUND3(Rc, Rd, Re, Ra, Rb)
ROUND3(Rb, Rc, Rd, Re, Ra)
SUB.S $1, Rctr
BNE loop3
MOVW $0xCA62C1D6, Rconst
MOVW $4, Rctr
loop4: ROUND4(Ra, Rb, Rc, Rd, Re)
ROUND4(Re, Ra, Rb, Rc, Rd)
ROUND4(Rd, Re, Ra, Rb, Rc)
ROUND4(Rc, Rd, Re, Ra, Rb)
ROUND4(Rb, Rc, Rd, Re, Ra)
SUB.S $1, Rctr
BNE loop4
// Accumulate - restoring registers from SP+4
MOVM.IB (R13), [Rt0,Rt1,Rt2,Rctr,Rw]
ADD Rt0, Ra
ADD Rt1, Rb
ADD Rt2, Rc
ADD Rctr, Rd
ADD Rw, Re
MOVW p_end, Rt0
CMP Rt0, Rdata
BLO loop
// Save final SHA-1 accumulator
MOVW dig+0(FP), Rt0
MOVM.IA [Ra,Rb,Rc,Rd,Re], (Rt0)
RET
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