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// Copyright 2019 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.
// +build gc,!purego
#include "textflag.h"
// This was ported from the amd64 implementation.
#define POLY1305_ADD(msg, h0, h1, h2, t0, t1, t2) \
MOVD (msg), t0; \
MOVD 8(msg), t1; \
MOVD $1, t2; \
ADDC t0, h0, h0; \
ADDE t1, h1, h1; \
ADDE t2, h2; \
ADD $16, msg
#define POLY1305_MUL(h0, h1, h2, r0, r1, t0, t1, t2, t3, t4, t5) \
MULLD r0, h0, t0; \
MULLD r0, h1, t4; \
MULHDU r0, h0, t1; \
MULHDU r0, h1, t5; \
ADDC t4, t1, t1; \
MULLD r0, h2, t2; \
ADDZE t5; \
MULHDU r1, h0, t4; \
MULLD r1, h0, h0; \
ADD t5, t2, t2; \
ADDC h0, t1, t1; \
MULLD h2, r1, t3; \
ADDZE t4, h0; \
MULHDU r1, h1, t5; \
MULLD r1, h1, t4; \
ADDC t4, t2, t2; \
ADDE t5, t3, t3; \
ADDC h0, t2, t2; \
MOVD $-4, t4; \
MOVD t0, h0; \
MOVD t1, h1; \
ADDZE t3; \
ANDCC $3, t2, h2; \
AND t2, t4, t0; \
ADDC t0, h0, h0; \
ADDE t3, h1, h1; \
SLD $62, t3, t4; \
SRD $2, t2; \
ADDZE h2; \
OR t4, t2, t2; \
SRD $2, t3; \
ADDC t2, h0, h0; \
ADDE t3, h1, h1; \
DATA ·poly1305Mask<>+0x00(SB)/8, $0x0FFFFFFC0FFFFFFF
DATA ·poly1305Mask<>+0x08(SB)/8, $0x0FFFFFFC0FFFFFFC
GLOBL ·poly1305Mask<>(SB), RODATA, $16
// func update(state *[7]uint64, msg []byte)
TEXT ·update(SB), $0-32
MOVD state+0(FP), R3
MOVD msg_base+8(FP), R4
MOVD msg_len+16(FP), R5
MOVD 0(R3), R8 // h0
MOVD 8(R3), R9 // h1
MOVD 16(R3), R10 // h2
MOVD 24(R3), R11 // r0
MOVD 32(R3), R12 // r1
CMP R5, $16
BLT bytes_between_0_and_15
POLY1305_ADD(R4, R8, R9, R10, R20, R21, R22)
POLY1305_MUL(R8, R9, R10, R11, R12, R16, R17, R18, R14, R20, R21)
ADD $-16, R5
CMP R5, $16
BGE loop
CMP $0, R5
BEQ done
MOVD $0, R16 // h0
MOVD $0, R17 // h1
CMP R5, $8
BLE just1
MOVD $8, R21
SUB R21, R5, R21
// Greater than 8 -- load the rightmost remaining bytes in msg
// and put into R17 (h1)
MOVD (R4)(R21), R17
MOVD $16, R22
// Find the offset to those bytes
SUB R5, R22, R22
SLD $3, R22
// Shift to get only the bytes in msg
SRD R22, R17, R17
// Put 1 at high end
MOVD $1, R23
SLD $3, R21
SLD R21, R23, R23
OR R23, R17, R17
// Remainder is 8
MOVD $8, R5
CMP R5, $8
BLT less8
// Exactly 8
MOVD (R4), R16
CMP $0, R17
// Check if we've already set R17; if not
// set 1 to indicate end of msg.
BNE carry
MOVD $1, R17
BR carry
MOVD $0, R16 // h0
MOVD $0, R22 // shift count
CMP R5, $4
BLT less4
MOVWZ (R4), R16
ADD $4, R4
ADD $-4, R5
MOVD $32, R22
CMP R5, $2
BLT less2
MOVHZ (R4), R21
SLD R22, R21, R21
OR R16, R21, R16
ADD $16, R22
ADD $-2, R5
ADD $2, R4
CMP $0, R5
BEQ insert1
MOVBZ (R4), R21
SLD R22, R21, R21
OR R16, R21, R16
ADD $8, R22
// Insert 1 at end of msg
MOVD $1, R21
SLD R22, R21, R21
OR R16, R21, R16
// Add new values to h0, h1, h2
ADDC R16, R8
ADDE R17, R9
ADDE $0, R10
MOVD $16, R5
ADD R5, R4
BR multiply
// Save h0, h1, h2 in state
MOVD R8, 0(R3)
MOVD R9, 8(R3)
MOVD R10, 16(R3)