//   ⎡x / c⎤ = ⎣x * m / 2^(n+s)⎦ + 1
// (TODO: derivation?)
//
// The multiply is a bit odd, as it is a signed n-bit value
// times an unsigned n-bit value.  For n smaller than the
// word size, we can extend x and m appropriately and use the
// signed multiply instruction.  For n == word size,
// we must use the signed multiply high and correct
// the result by adding x*2^n.
//
// Adding 1 if x<0 is done by subtracting x>>(n-1).

// "sign", so Add32 can be used both for signed and unsigned 32-bit
// addition.

// Signed/unsigned is explicit with the extension ops
// (SignExt*/ZeroExt*) and implicit as the arg to some opcodes
// (e.g. the second argument to shifts is unsigned). If not mentioned,
// all args take signed inputs, or don't care whether their inputs
// are signed or unsigned.

var genericOps = []opData{
	// 2-input arithmetic

		{name: "SRLVconst", argLength: 1, reg: gp11, asm: "SRLV", aux: "Int64"}, // arg0 >> auxInt, unsigned
		{name: "SRAV", argLength: 2, reg: gp21, asm: "SRAV"},                    // arg0 >> arg1, signed, shift amount is mod 64
		{name: "SRAVconst", argLength: 1, reg: gp11, asm: "SRAV", aux: "Int64"}, // arg0 >> auxInt, signed

		// comparisons

		// cannot appear in the generated assembly.
		{name: "FlagEQ"},     // equal
		{name: "FlagLT_ULT"}, // signed < and unsigned <
		{name: "FlagLT_UGT"}, // signed < and unsigned >
		{name: "FlagGT_UGT"}, // signed > and unsigned >
		{name: "FlagGT_ULT"}, // signed > and unsigned <

		// Atomic loads.  These are just normal loads but return <value,memory> tuples
		// so they can be properly ordered with other loads.

	}
	return false
}

func areMergeableInequalities(x, y *Value) bool {
	// We need both inequalities to be either in the signed or unsigned domain.
	// TODO(mundaym): it would also be good to merge when we have an Eq op that
	// could be transformed into a Less/Leq. For example in the unsigned
	// domain 'x == 0 || 3 < x' is equivalent to 'x <= 0 || 3 < x'
	inequalityChecks := [...]func(*Value) bool{
		isSignedInequality,

		{name: "SGTU", argLength: 2, reg: gp21, asm: "SGTU", typ: "Bool"},                    // 1 if arg0 > arg1 (unsigned), 0 otherwise
		{name: "SGTUconst", argLength: 1, reg: gp11, asm: "SGTU", aux: "Int32", typ: "Bool"}, // 1 if auxInt > arg0 (unsigned), 0 otherwise
		{name: "SGTUzero", argLength: 1, reg: gp11, asm: "SGTU", typ: "Bool"},                // 1 if arg0 > 0 (unsigned), 0 otherwise

// POSIX specifies a sum of the unsigned byte values, but the Sun tar used
// signed byte values.
// We compute and return both.
func (b *block) computeChecksum() (unsigned, signed int64) {
	for i, c := range b {
		if 148 <= i && i < 156 {
			c = ' ' // Treat the checksum field itself as all spaces.
		}
		unsigned += int64(c)
		signed += int64(int8(c))
	}
	return unsigned, signed
}

// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <process.h>
#include "_cgo_export.h"

__stdcall
static unsigned int
addThread(void *p)
{
	int i, max;
	
	max = *(int*)p;
	for(i=0; i<max; i++)
		Add(i);
	return 0;
}

void
doAdd(int max, int nthread)
{
	enum { MaxThread = 20 };
	int i;

	MOVW	$1, X5				// ERROR "unsupported constant load"
	MOVF	$1, X5				// ERROR "unsupported constant load"
	MOVBU	X5, (X6)			// ERROR "unsupported unsigned store"
	MOVHU	X5, (X6)			// ERROR "unsupported unsigned store"
	MOVWU	X5, (X6)			// ERROR "unsupported unsigned store"
	MOVF	F0, F1, F2			// ERROR "illegal MOV instruction"
	MOVD	F0, F1, F2			// ERROR "illegal MOV instruction"
	MOV	X10, X11, X12			// ERROR "illegal MOV instruction"

		{name: "LessEqualU", argLength: 1, reg: readflags},       // bool, true flags encode unsigned x<=y false otherwise.
		{name: "GreaterThanU", argLength: 1, reg: readflags},     // bool, true flags encode unsigned x>y false otherwise.
		{name: "GreaterEqualU", argLength: 1, reg: readflags},    // bool, true flags encode unsigned x>=y false otherwise.