// Copyright 2013 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.

#include "textflag.h"

// SHA256 block routine. See sha256block.go for Go equivalent.
//
// The algorithm is detailed in FIPS 180-4:
//
//  https://csrc.nist.gov/publications/fips/fips180-4/fips-180-4.pdf

// Wt = Mt; for 0 <= t <= 15
// Wt = SIGMA1(Wt-2) + SIGMA0(Wt-15) + Wt-16; for 16 <= t <= 63
//
// a = H0
// b = H1
// c = H2
// d = H3
// e = H4
// f = H5
// g = H6
// h = H7
//
// for t = 0 to 63 {
//    T1 = h + BIGSIGMA1(e) + Ch(e,f,g) + Kt + Wt
//    T2 = BIGSIGMA0(a) + Maj(a,b,c)
//    h = g
//    g = f
//    f = e
//    e = d + T1
//    d = c
//    c = b
//    b = a
//    a = T1 + T2
// }
//
// H0 = a + H0
// H1 = b + H1
// H2 = c + H2
// H3 = d + H3
// H4 = e + H4
// H5 = f + H5
// H6 = g + H6
// H7 = h + H7

// Wt = Mt; for 0 <= t <= 15
#define MSGSCHEDULE0(index) \
	MOVL	(index*4)(SI), AX; \
	BSWAPL	AX; \
	MOVL	AX, (index*4)(BP)

// Wt = SIGMA1(Wt-2) + Wt-7 + SIGMA0(Wt-15) + Wt-16; for 16 <= t <= 63
//   SIGMA0(x) = ROTR(7,x) XOR ROTR(18,x) XOR SHR(3,x)
//   SIGMA1(x) = ROTR(17,x) XOR ROTR(19,x) XOR SHR(10,x)
#define MSGSCHEDULE1(index) \
	MOVL	((index-2)*4)(BP), AX; \
	MOVL	AX, CX; \
	RORL	$17, AX; \
	MOVL	CX, DX; \
	RORL	$19, CX; \
	SHRL	$10, DX; \
	MOVL	((index-15)*4)(BP), BX; \
	XORL	CX, AX; \
	MOVL	BX, CX; \
	XORL	DX, AX; \
	RORL	$7, BX; \
	MOVL	CX, DX; \
	SHRL	$3, DX; \
	RORL	$18, CX; \
	ADDL	((index-7)*4)(BP), AX; \
	XORL	CX, BX; \
	XORL	DX, BX; \
	ADDL	((index-16)*4)(BP), BX; \
	ADDL	BX, AX; \
	MOVL	AX, ((index)*4)(BP)

// Calculate T1 in AX - uses AX, CX and DX registers.
// h is also used as an accumulator. Wt is passed in AX.
//   T1 = h + BIGSIGMA1(e) + Ch(e, f, g) + Kt + Wt
//     BIGSIGMA1(x) = ROTR(6,x) XOR ROTR(11,x) XOR ROTR(25,x)
//     Ch(x, y, z) = (x AND y) XOR (NOT x AND z)
#define SHA256T1(const, e, f, g, h) \
	ADDL	AX, h; \
	MOVL	e, AX; \
	ADDL	$const, h; \
	MOVL	e, CX; \
	RORL	$6, AX; \
	MOVL	e, DX; \
	RORL	$11, CX; \
	XORL	CX, AX; \
	MOVL	e, CX; \
	RORL	$25, DX; \
	ANDL	f, CX; \
	XORL	AX, DX; \
	MOVL	e, AX; \
	NOTL	AX; \
	ADDL	DX, h; \
	ANDL	g, AX; \
	XORL	CX, AX; \
	ADDL	h, AX

// Calculate T2 in BX - uses BX, CX, DX and DI registers.
//   T2 = BIGSIGMA0(a) + Maj(a, b, c)
//     BIGSIGMA0(x) = ROTR(2,x) XOR ROTR(13,x) XOR ROTR(22,x)
//     Maj(x, y, z) = (x AND y) XOR (x AND z) XOR (y AND z)
#define SHA256T2(a, b, c) \
	MOVL	a, DI; \
	MOVL	c, BX; \
	RORL	$2, DI; \
	MOVL	a, DX; \
	ANDL	b, BX; \
	RORL	$13, DX; \
	MOVL	a, CX; \
	ANDL	c, CX; \
	XORL	DX, DI; \
	XORL	CX, BX; \
	MOVL	a, DX; \
	MOVL	b, CX; \
	RORL	$22, DX; \
	ANDL	a, CX; \
	XORL	CX, BX; \
	XORL	DX, DI; \
	ADDL	DI, BX

// Calculate T1 and T2, then e = d + T1 and a = T1 + T2.
// The values for e and a are stored in d and h, ready for rotation.
#define SHA256ROUND(index, const, a, b, c, d, e, f, g, h) \
	SHA256T1(const, e, f, g, h); \
	SHA256T2(a, b, c); \
	MOVL	BX, h; \
	ADDL	AX, d; \
	ADDL	AX, h

#define SHA256ROUND0(index, const, a, b, c, d, e, f, g, h) \
	MSGSCHEDULE0(index); \
	SHA256ROUND(index, const, a, b, c, d, e, f, g, h)

#define SHA256ROUND1(index, const, a, b, c, d, e, f, g, h) \
	MSGSCHEDULE1(index); \
	SHA256ROUND(index, const, a, b, c, d, e, f, g, h)

TEXT ·block(SB), 0, $536-32
	MOVQ p_base+8(FP), SI
	MOVQ p_len+16(FP), DX
	SHRQ $6, DX
	SHLQ $6, DX

	LEAQ (SI)(DX*1), DI
	MOVQ DI, 256(SP)
	CMPQ SI, DI
	JEQ  end

	MOVQ dig+0(FP), BP
	MOVL (0*4)(BP), R8  // a = H0
	MOVL (1*4)(BP), R9  // b = H1
	MOVL (2*4)(BP), R10 // c = H2
	MOVL (3*4)(BP), R11 // d = H3
	MOVL (4*4)(BP), R12 // e = H4
	MOVL (5*4)(BP), R13 // f = H5
	MOVL (6*4)(BP), R14 // g = H6
	MOVL (7*4)(BP), R15 // h = H7

loop:
	MOVQ SP, BP

	SHA256ROUND0(0, 0x428a2f98, R8, R9, R10, R11, R12, R13, R14, R15)
	SHA256ROUND0(1, 0x71374491, R15, R8, R9, R10, R11, R12, R13, R14)
	SHA256ROUND0(2, 0xb5c0fbcf, R14, R15, R8, R9, R10, R11, R12, R13)
	SHA256ROUND0(3, 0xe9b5dba5, R13, R14, R15, R8, R9, R10, R11, R12)
	SHA256ROUND0(4, 0x3956c25b, R12, R13, R14, R15, R8, R9, R10, R11)
	SHA256ROUND0(5, 0x59f111f1, R11, R12, R13, R14, R15, R8, R9, R10)
	SHA256ROUND0(6, 0x923f82a4, R10, R11, R12, R13, R14, R15, R8, R9)
	SHA256ROUND0(7, 0xab1c5ed5, R9, R10, R11, R12, R13, R14, R15, R8)
	SHA256ROUND0(8, 0xd807aa98, R8, R9, R10, R11, R12, R13, R14, R15)
	SHA256ROUND0(9, 0x12835b01, R15, R8, R9, R10, R11, R12, R13, R14)
	SHA256ROUND0(10, 0x243185be, R14, R15, R8, R9, R10, R11, R12, R13)
	SHA256ROUND0(11, 0x550c7dc3, R13, R14, R15, R8, R9, R10, R11, R12)
	SHA256ROUND0(12, 0x72be5d74, R12, R13, R14, R15, R8, R9, R10, R11)
	SHA256ROUND0(13, 0x80deb1fe, R11, R12, R13, R14, R15, R8, R9, R10)
	SHA256ROUND0(14, 0x9bdc06a7, R10, R11, R12, R13, R14, R15, R8, R9)
	SHA256ROUND0(15, 0xc19bf174, R9, R10, R11, R12, R13, R14, R15, R8)

	SHA256ROUND1(16, 0xe49b69c1, R8, R9, R10, R11, R12, R13, R14, R15)
	SHA256ROUND1(17, 0xefbe4786, R15, R8, R9, R10, R11, R12, R13, R14)
	SHA256ROUND1(18, 0x0fc19dc6, R14, R15, R8, R9, R10, R11, R12, R13)
	SHA256ROUND1(19, 0x240ca1cc, R13, R14, R15, R8, R9, R10, R11, R12)
	SHA256ROUND1(20, 0x2de92c6f, R12, R13, R14, R15, R8, R9, R10, R11)
	SHA256ROUND1(21, 0x4a7484aa, R11, R12, R13, R14, R15, R8, R9, R10)
	SHA256ROUND1(22, 0x5cb0a9dc, R10, R11, R12, R13, R14, R15, R8, R9)
	SHA256ROUND1(23, 0x76f988da, R9, R10, R11, R12, R13, R14, R15, R8)
	SHA256ROUND1(24, 0x983e5152, R8, R9, R10, R11, R12, R13, R14, R15)
	SHA256ROUND1(25, 0xa831c66d, R15, R8, R9, R10, R11, R12, R13, R14)
	SHA256ROUND1(26, 0xb00327c8, R14, R15, R8, R9, R10, R11, R12, R13)
	SHA256ROUND1(27, 0xbf597fc7, R13, R14, R15, R8, R9, R10, R11, R12)
	SHA256ROUND1(28, 0xc6e00bf3, R12, R13, R14, R15, R8, R9, R10, R11)
	SHA256ROUND1(29, 0xd5a79147, R11, R12, R13, R14, R15, R8, R9, R10)
	SHA256ROUND1(30, 0x06ca6351, R10, R11, R12, R13, R14, R15, R8, R9)
	SHA256ROUND1(31, 0x14292967, R9, R10, R11, R12, R13, R14, R15, R8)
	SHA256ROUND1(32, 0x27b70a85, R8, R9, R10, R11, R12, R13, R14, R15)
	SHA256ROUND1(33, 0x2e1b2138, R15, R8, R9, R10, R11, R12, R13, R14)
	SHA256ROUND1(34, 0x4d2c6dfc, R14, R15, R8, R9, R10, R11, R12, R13)
	SHA256ROUND1(35, 0x53380d13, R13, R14, R15, R8, R9, R10, R11, R12)
	SHA256ROUND1(36, 0x650a7354, R12, R13, R14, R15, R8, R9, R10, R11)
	SHA256ROUND1(37, 0x766a0abb, R11, R12, R13, R14, R15, R8, R9, R10)
	SHA256ROUND1(38, 0x81c2c92e, R10, R11, R12, R13, R14, R15, R8, R9)
	SHA256ROUND1(39, 0x92722c85, R9, R10, R11, R12, R13, R14, R15, R8)
	SHA256ROUND1(40, 0xa2bfe8a1, R8, R9, R10, R11, R12, R13, R14, R15)
	SHA256ROUND1(41, 0xa81a664b, R15, R8, R9, R10, R11, R12, R13, R14)
	SHA256ROUND1(42, 0xc24b8b70, R14, R15, R8, R9, R10, R11, R12, R13)
	SHA256ROUND1(43, 0xc76c51a3, R13, R14, R15, R8, R9, R10, R11, R12)
	SHA256ROUND1(44, 0xd192e819, R12, R13, R14, R15, R8, R9, R10, R11)
	SHA256ROUND1(45, 0xd6990624, R11, R12, R13, R14, R15, R8, R9, R10)
	SHA256ROUND1(46, 0xf40e3585, R10, R11, R12, R13, R14, R15, R8, R9)
	SHA256ROUND1(47, 0x106aa070, R9, R10, R11, R12, R13, R14, R15, R8)
	SHA256ROUND1(48, 0x19a4c116, R8, R9, R10, R11, R12, R13, R14, R15)
	SHA256ROUND1(49, 0x1e376c08, R15, R8, R9, R10, R11, R12, R13, R14)
	SHA256ROUND1(50, 0x2748774c, R14, R15, R8, R9, R10, R11, R12, R13)
	SHA256ROUND1(51, 0x34b0bcb5, R13, R14, R15, R8, R9, R10, R11, R12)
	SHA256ROUND1(52, 0x391c0cb3, R12, R13, R14, R15, R8, R9, R10, R11)
	SHA256ROUND1(53, 0x4ed8aa4a, R11, R12, R13, R14, R15, R8, R9, R10)
	SHA256ROUND1(54, 0x5b9cca4f, R10, R11, R12, R13, R14, R15, R8, R9)
	SHA256ROUND1(55, 0x682e6ff3, R9, R10, R11, R12, R13, R14, R15, R8)
	SHA256ROUND1(56, 0x748f82ee, R8, R9, R10, R11, R12, R13, R14, R15)
	SHA256ROUND1(57, 0x78a5636f, R15, R8, R9, R10, R11, R12, R13, R14)
	SHA256ROUND1(58, 0x84c87814, R14, R15, R8, R9, R10, R11, R12, R13)
	SHA256ROUND1(59, 0x8cc70208, R13, R14, R15, R8, R9, R10, R11, R12)
	SHA256ROUND1(60, 0x90befffa, R12, R13, R14, R15, R8, R9, R10, R11)
	SHA256ROUND1(61, 0xa4506ceb, R11, R12, R13, R14, R15, R8, R9, R10)
	SHA256ROUND1(62, 0xbef9a3f7, R10, R11, R12, R13, R14, R15, R8, R9)
	SHA256ROUND1(63, 0xc67178f2, R9, R10, R11, R12, R13, R14, R15, R8)

	MOVQ dig+0(FP), BP
	ADDL (0*4)(BP), R8  // H0 = a + H0
	MOVL R8, (0*4)(BP)
	ADDL (1*4)(BP), R9  // H1 = b + H1
	MOVL R9, (1*4)(BP)
	ADDL (2*4)(BP), R10 // H2 = c + H2
	MOVL R10, (2*4)(BP)
	ADDL (3*4)(BP), R11 // H3 = d + H3
	MOVL R11, (3*4)(BP)
	ADDL (4*4)(BP), R12 // H4 = e + H4
	MOVL R12, (4*4)(BP)
	ADDL (5*4)(BP), R13 // H5 = f + H5
	MOVL R13, (5*4)(BP)
	ADDL (6*4)(BP), R14 // H6 = g + H6
	MOVL R14, (6*4)(BP)
	ADDL (7*4)(BP), R15 // H7 = h + H7
	MOVL R15, (7*4)(BP)

	ADDQ $64, SI
	CMPQ SI, 256(SP)
	JB   loop

end:
	RET

// shuffle byte order from LE to BE
DATA flip_mask<>+0x00(SB)/8, $0x0405060700010203
DATA flip_mask<>+0x08(SB)/8, $0x0c0d0e0f08090a0b
DATA flip_mask<>+0x10(SB)/8, $0x0405060700010203
DATA flip_mask<>+0x18(SB)/8, $0x0c0d0e0f08090a0b
GLOBL flip_mask<>(SB), 8, $32

// shuffle xBxA -> 00BA
DATA shuff_00BA<>+0x00(SB)/8, $0x0b0a090803020100
DATA shuff_00BA<>+0x08(SB)/8, $0xFFFFFFFFFFFFFFFF
DATA shuff_00BA<>+0x10(SB)/8, $0x0b0a090803020100
DATA shuff_00BA<>+0x18(SB)/8, $0xFFFFFFFFFFFFFFFF
GLOBL shuff_00BA<>(SB), 8, $32

// shuffle xDxC -> DC00
DATA shuff_DC00<>+0x00(SB)/8, $0xFFFFFFFFFFFFFFFF
DATA shuff_DC00<>+0x08(SB)/8, $0x0b0a090803020100
DATA shuff_DC00<>+0x10(SB)/8, $0xFFFFFFFFFFFFFFFF
DATA shuff_DC00<>+0x18(SB)/8, $0x0b0a090803020100
GLOBL shuff_DC00<>(SB), 8, $32

// Round specific constants
DATA K256<>+0x00(SB)/4, $0x428a2f98 // k1
DATA K256<>+0x04(SB)/4, $0x71374491 // k2
DATA K256<>+0x08(SB)/4, $0xb5c0fbcf // k3
DATA K256<>+0x0c(SB)/4, $0xe9b5dba5 // k4
DATA K256<>+0x10(SB)/4, $0x428a2f98 // k1
DATA K256<>+0x14(SB)/4, $0x71374491 // k2
DATA K256<>+0x18(SB)/4, $0xb5c0fbcf // k3
DATA K256<>+0x1c(SB)/4, $0xe9b5dba5 // k4

DATA K256<>+0x20(SB)/4, $0x3956c25b // k5 - k8
DATA K256<>+0x24(SB)/4, $0x59f111f1
DATA K256<>+0x28(SB)/4, $0x923f82a4
DATA K256<>+0x2c(SB)/4, $0xab1c5ed5
DATA K256<>+0x30(SB)/4, $0x3956c25b
DATA K256<>+0x34(SB)/4, $0x59f111f1
DATA K256<>+0x38(SB)/4, $0x923f82a4
DATA K256<>+0x3c(SB)/4, $0xab1c5ed5

DATA K256<>+0x40(SB)/4, $0xd807aa98 // k9 - k12
DATA K256<>+0x44(SB)/4, $0x12835b01
DATA K256<>+0x48(SB)/4, $0x243185be
DATA K256<>+0x4c(SB)/4, $0x550c7dc3
DATA K256<>+0x50(SB)/4, $0xd807aa98
DATA K256<>+0x54(SB)/4, $0x12835b01
DATA K256<>+0x58(SB)/4, $0x243185be
DATA K256<>+0x5c(SB)/4, $0x550c7dc3

DATA K256<>+0x60(SB)/4, $0x72be5d74 // k13 - k16
DATA K256<>+0x64(SB)/4, $0x80deb1fe
DATA K256<>+0x68(SB)/4, $0x9bdc06a7
DATA K256<>+0x6c(SB)/4, $0xc19bf174
DATA K256<>+0x70(SB)/4, $0x72be5d74
DATA K256<>+0x74(SB)/4, $0x80deb1fe
DATA K256<>+0x78(SB)/4, $0x9bdc06a7
DATA K256<>+0x7c(SB)/4, $0xc19bf174

DATA K256<>+0x80(SB)/4, $0xe49b69c1 // k17 - k20
DATA K256<>+0x84(SB)/4, $0xefbe4786
DATA K256<>+0x88(SB)/4, $0x0fc19dc6
DATA K256<>+0x8c(SB)/4, $0x240ca1cc
DATA K256<>+0x90(SB)/4, $0xe49b69c1
DATA K256<>+0x94(SB)/4, $0xefbe4786
DATA K256<>+0x98(SB)/4, $0x0fc19dc6
DATA K256<>+0x9c(SB)/4, $0x240ca1cc

DATA K256<>+0xa0(SB)/4, $0x2de92c6f // k21 - k24
DATA K256<>+0xa4(SB)/4, $0x4a7484aa
DATA K256<>+0xa8(SB)/4, $0x5cb0a9dc
DATA K256<>+0xac(SB)/4, $0x76f988da
DATA K256<>+0xb0(SB)/4, $0x2de92c6f
DATA K256<>+0xb4(SB)/4, $0x4a7484aa
DATA K256<>+0xb8(SB)/4, $0x5cb0a9dc
DATA K256<>+0xbc(SB)/4, $0x76f988da

DATA K256<>+0xc0(SB)/4, $0x983e5152 // k25 - k28
DATA K256<>+0xc4(SB)/4, $0xa831c66d
DATA K256<>+0xc8(SB)/4, $0xb00327c8
DATA K256<>+0xcc(SB)/4, $0xbf597fc7
DATA K256<>+0xd0(SB)/4, $0x983e5152
DATA K256<>+0xd4(SB)/4, $0xa831c66d
DATA K256<>+0xd8(SB)/4, $0xb00327c8
DATA K256<>+0xdc(SB)/4, $0xbf597fc7

DATA K256<>+0xe0(SB)/4, $0xc6e00bf3 // k29 - k32
DATA K256<>+0xe4(SB)/4, $0xd5a79147
DATA K256<>+0xe8(SB)/4, $0x06ca6351
DATA K256<>+0xec(SB)/4, $0x14292967
DATA K256<>+0xf0(SB)/4, $0xc6e00bf3
DATA K256<>+0xf4(SB)/4, $0xd5a79147
DATA K256<>+0xf8(SB)/4, $0x06ca6351
DATA K256<>+0xfc(SB)/4, $0x14292967

DATA K256<>+0x100(SB)/4, $0x27b70a85
DATA K256<>+0x104(SB)/4, $0x2e1b2138
DATA K256<>+0x108(SB)/4, $0x4d2c6dfc
DATA K256<>+0x10c(SB)/4, $0x53380d13
DATA K256<>+0x110(SB)/4, $0x27b70a85
DATA K256<>+0x114(SB)/4, $0x2e1b2138
DATA K256<>+0x118(SB)/4, $0x4d2c6dfc
DATA K256<>+0x11c(SB)/4, $0x53380d13

DATA K256<>+0x120(SB)/4, $0x650a7354
DATA K256<>+0x124(SB)/4, $0x766a0abb
DATA K256<>+0x128(SB)/4, $0x81c2c92e
DATA K256<>+0x12c(SB)/4, $0x92722c85
DATA K256<>+0x130(SB)/4, $0x650a7354
DATA K256<>+0x134(SB)/4, $0x766a0abb
DATA K256<>+0x138(SB)/4, $0x81c2c92e
DATA K256<>+0x13c(SB)/4, $0x92722c85

DATA K256<>+0x140(SB)/4, $0xa2bfe8a1
DATA K256<>+0x144(SB)/4, $0xa81a664b
DATA K256<>+0x148(SB)/4, $0xc24b8b70
DATA K256<>+0x14c(SB)/4, $0xc76c51a3
DATA K256<>+0x150(SB)/4, $0xa2bfe8a1
DATA K256<>+0x154(SB)/4, $0xa81a664b
DATA K256<>+0x158(SB)/4, $0xc24b8b70
DATA K256<>+0x15c(SB)/4, $0xc76c51a3

DATA K256<>+0x160(SB)/4, $0xd192e819
DATA K256<>+0x164(SB)/4, $0xd6990624
DATA K256<>+0x168(SB)/4, $0xf40e3585
DATA K256<>+0x16c(SB)/4, $0x106aa070
DATA K256<>+0x170(SB)/4, $0xd192e819
DATA K256<>+0x174(SB)/4, $0xd6990624
DATA K256<>+0x178(SB)/4, $0xf40e3585
DATA K256<>+0x17c(SB)/4, $0x106aa070

DATA K256<>+0x180(SB)/4, $0x19a4c116
DATA K256<>+0x184(SB)/4, $0x1e376c08
DATA K256<>+0x188(SB)/4, $0x2748774c
DATA K256<>+0x18c(SB)/4, $0x34b0bcb5
DATA K256<>+0x190(SB)/4, $0x19a4c116
DATA K256<>+0x194(SB)/4, $0x1e376c08
DATA K256<>+0x198(SB)/4, $0x2748774c
DATA K256<>+0x19c(SB)/4, $0x34b0bcb5

DATA K256<>+0x1a0(SB)/4, $0x391c0cb3
DATA K256<>+0x1a4(SB)/4, $0x4ed8aa4a
DATA K256<>+0x1a8(SB)/4, $0x5b9cca4f
DATA K256<>+0x1ac(SB)/4, $0x682e6ff3
DATA K256<>+0x1b0(SB)/4, $0x391c0cb3
DATA K256<>+0x1b4(SB)/4, $0x4ed8aa4a
DATA K256<>+0x1b8(SB)/4, $0x5b9cca4f
DATA K256<>+0x1bc(SB)/4, $0x682e6ff3

DATA K256<>+0x1c0(SB)/4, $0x748f82ee
DATA K256<>+0x1c4(SB)/4, $0x78a5636f
DATA K256<>+0x1c8(SB)/4, $0x84c87814
DATA K256<>+0x1cc(SB)/4, $0x8cc70208
DATA K256<>+0x1d0(SB)/4, $0x748f82ee
DATA K256<>+0x1d4(SB)/4, $0x78a5636f
DATA K256<>+0x1d8(SB)/4, $0x84c87814
DATA K256<>+0x1dc(SB)/4, $0x8cc70208

DATA K256<>+0x1e0(SB)/4, $0x90befffa
DATA K256<>+0x1e4(SB)/4, $0xa4506ceb
DATA K256<>+0x1e8(SB)/4, $0xbef9a3f7
DATA K256<>+0x1ec(SB)/4, $0xc67178f2
DATA K256<>+0x1f0(SB)/4, $0x90befffa
DATA K256<>+0x1f4(SB)/4, $0xa4506ceb
DATA K256<>+0x1f8(SB)/4, $0xbef9a3f7
DATA K256<>+0x1fc(SB)/4, $0xc67178f2

GLOBL K256<>(SB), (NOPTR + RODATA), $512