MOVL	$SYS_sigaltstack, AX
	INT	$0x80
	JAE	2(PC)
	MOVL	$0xf1, 0xf1  // crash
	RET

TEXT runtime·usleep(SB),NOSPLIT,$20
	MOVL	$0, DX
	MOVL	usec+0(FP), AX
	MOVL	$1000000, CX
	DIVL	CX
	MOVL	AX, 12(SP)		// tv_sec
	MOVL	$1000, AX
	MULL	DX
	MOVL	AX, 16(SP)		// tv_nsec

	MOVL	$0, 0(SP)
	LEAL	12(SP), AX
	MOVL	AX, 4(SP)		// arg 1 - rqtp
	MOVL	$0, 8(SP)		// arg 2 - rmtp

	SYSCALL
	JCC	2(PC)
	NEGQ	AX			// caller expects negative errno
	MOVL	AX, ret+24(FP)
	RET

TEXT runtime·usleep(SB),NOSPLIT,$16
	MOVL	$0, DX
	MOVL	usec+0(FP), AX
	MOVL	$1000000, CX
	DIVL	CX
	MOVQ	AX, 0(SP)		// tv_sec
	MOVL	$1000, AX
	MULL	DX
	MOVQ	AX, 8(SP)		// tv_nsec

	MOVQ	SP, DI			// arg 1 - rqtp
	MOVQ	$0, SI			// arg 2 - rmtp
	MOVL	$SYS___nanosleep50, AX
	SYSCALL
	RET

	INT	$0x80
	JAE	2(PC)
	NEGL	AX			// caller expects negative errno
	MOVL	AX, ret+12(FP)
	RET

TEXT runtime·usleep(SB),NOSPLIT,$24
	MOVL	$0, DX
	MOVL	usec+0(FP), AX
	MOVL	$1000000, CX
	DIVL	CX
	MOVL	AX, 12(SP)		// tv_sec - l32
	MOVL	$0, 16(SP)		// tv_sec - h32
	MOVL	$1000, AX
	MULL	DX
	MOVL	AX, 20(SP)		// tv_nsec

	MOVL	$0, 0(SP)
	LEAL	12(SP), AX
	MOVL	AX, 4(SP)		// arg 1 - rqtp

  if (rank == 1) {
    int64_t dim0 = input_ty.getDimSize(0);
    if (dim0 != ShapedType::kDynamic && dim0 != 4 && dim0 != 2)
      return op.emitOpError("requires 1D input of size 4 or size 2");
  }

  if (rank == 2) {
    int64_t dim0 = input_ty.getDimSize(0);
    if (dim0 != ShapedType::kDynamic && dim0 != 4)
      return op.emitOpError(

	MOVQ	old+8(FP), SI
	MOVQ	$53, AX
	SYSCALL
	JCC	2(PC)
	MOVL	$0xf1, 0xf1  // crash
	RET

TEXT runtime·usleep(SB),NOSPLIT,$16
	MOVL	$0, DX
	MOVL	usec+0(FP), AX
	MOVL	$1000000, CX
	DIVL	CX
	MOVQ	AX, 0(SP)		// tv_sec
	MOVL	$1000, AX
	MULL	DX
	MOVQ	AX, 8(SP)		// tv_nsec

	MOVQ	SP, DI			// arg 1 - rqtp
	MOVQ	$0, SI			// arg 2 - rmtp
	MOVL	$240, AX		// sys_nanosleep
	SYSCALL
	RET

		{name: "DIV", argLength: 2, reg: gp21, asm: "DIV", typ: "Int64"}, // arg0 / arg1
		{name: "DIVU", argLength: 2, reg: gp21, asm: "DIVU", typ: "UInt64"},
		{name: "DIVW", argLength: 2, reg: gp21, asm: "DIVW", typ: "Int32"},
		{name: "DIVUW", argLength: 2, reg: gp21, asm: "DIVUW", typ: "UInt32"},

	MULU	R21, R13	// 01b50019
	MULV	R19, R8		// 0113001c
	MULVU	R21, R13	// 01b5001d

//	LDIV rreg ',' rreg
//	{
//		outcode(int($1), &$2, 0, &$4);
//	}
	DIV	R18, R22	// 02d2001a
	DIVU	R14, R9		// 012e001b
	DIVV	R8, R13		// 01a8001e
	DIVVU	R16, R19	// 0270001f

//	LREM rreg ',' rreg
//	{
//		outcode(int($1), &$2, 0, &$4);
//	}
	REM	R18, R22	// 02d2001a
	REMU	R14, R9		// 012e001b

	i := x.bitLen()/log2(Word(base)) + 1 // +1: round up
	s := make([]byte, i)

	// don't destroy x
	q := nat(nil).set(x)

	// convert
	for len(q) > 0 {
		i--
		var r Word
		q, r = q.divW(q, Word(base))
		s[i] = digits[r]
	}

	return s[i:]
}

var strTests = []struct {
	x nat    // nat value to be converted
	b int    // conversion base
	s string // expected result
}{
	{nil, 2, "0"},

	if _, err := exec.LookPath("gcc"); err != nil {
		t.Skip("skipping test: gcc is missing")
	}

	tmpdir := t.TempDir()

	dir0, err := os.Getwd()
	if err != nil {
		t.Fatal(err)
	}
	defer os.Chdir(dir0)

	const src = `
#include <stdint.h>
#include <windows.h>

uintptr_t cfunc(void) {
   SetLastError(123);
   return 0;
}
`

        x))
    (Const64 <typ.UInt64> [umagic64(c).s-1]))

// Signed divide by a negative constant.  Rewrite to divide by a positive constant.
(Div8  <t> n (Const8  [c])) && c < 0 && c != -1<<7  => (Neg8  (Div8  <t> n (Const8  <t> [-c])))
(Div16 <t> n (Const16 [c])) && c < 0 && c != -1<<15 => (Neg16 (Div16 <t> n (Const16 <t> [-c])))