// Carry arithmetic, rotates, unsigned/signed division and bit tests: the
// scalar families GOROOT's big-number and crypto kernels use.  Every result
// is folded back so no instruction is dead.

#include "textflag.h"

// func carry(a, b uint64) uint64
TEXT ·carry(SB), NOSPLIT, $0-24
	MOVQ a+0(FP), AX
	MOVQ b+8(FP), BX
	ADDQ BX, AX
	ADCQ $0, AX
	MOVQ BX, CX
	SBBQ $1, CX
	ADCL BX, AX
	ADCB AL, BL
	ADCW $7, CX
	MOVQ AX, ret+16(FP)
	RET

// func borrow(a, b uint64) uint64
TEXT ·borrow(SB), NOSPLIT, $0-24
	MOVQ a+0(FP), AX
	MOVQ b+8(FP), BX
	SUBQ BX, AX
	SBBQ $0, AX
	SBBQ BX, CX
	MOVQ AX, ret+16(FP)
	RET

// func rot(x uint64, n uint32) uint64
TEXT ·rot(SB), NOSPLIT, $0-24
	MOVQ x+0(FP), AX
	MOVL n+8(FP), CX
	ROLQ CL, AX
	RORQ $7, AX
	ROLL $1, AX
	RORL CL, AX
	RCLQ $1, AX
	RCRQ CL, AX
	ROLW $3, AX
	SALQ $2, AX
	SALB $1, AX
	MOVQ AX, ret+8(FP)
	RET

// func muldiv(a, b uint64) uint64
TEXT ·muldiv(SB), NOSPLIT, $0-24
	MOVQ  a+0(FP), AX
	MOVQ  b+8(FP), BX
	MULQ  BX
	MULQ  (BX)
	MOVL  (BX), CX
	MULL  CX
	DIVQ  BX
	IDIVQ BX
	MOVL  a+0(FP), AX
	DIVL  CX
	IDIVL CX
	MOVQ  AX, ret+16(FP)
	RET

// func bitfield(w *uint64) uint64
TEXT ·bitfield(SB), NOSPLIT, $0-16
	MOVQ  (DI), AX
	MOVQ  (DI), CX
	BTQ   AX, CX
	BTQ   $3, (DI)
	BTL   AX, CX
	BTW   $1, CX
	BTSQ  $5, AX
	BTRQ  AX, CX
	BTCQ  $7, (DI)
	SETCS AL
	MOVQ  AX, ret+8(FP)
	RET