// Copyright 2009 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.

package arm

import (
	"cmd/compile/internal/ir"
	"cmd/compile/internal/objw"
	"cmd/compile/internal/types"
	"cmd/internal/obj"
	"cmd/internal/obj/arm"
)

func zerorange(pp *objw.Progs, p *obj.Prog, off, cnt int64, r0 *uint32) *obj.Prog {
	if cnt == 0 {
		return p
	}
	if *r0 == 0 {
		p = pp.Append(p, arm.AMOVW, obj.TYPE_CONST, 0, 0, obj.TYPE_REG, arm.REG_R0, 0)
		*r0 = 1
	}

	if cnt < int64(4*types.PtrSize) {
		for i := int64(0); i < cnt; i += int64(types.PtrSize) {
			p = pp.Append(p, arm.AMOVW, obj.TYPE_REG, arm.REG_R0, 0, obj.TYPE_MEM, arm.REGSP, 4+off+i)
		}
	} else if cnt <= int64(128*types.PtrSize) {
		p = pp.Append(p, arm.AADD, obj.TYPE_CONST, 0, 4+off, obj.TYPE_REG, arm.REG_R1, 0)
		p.Reg = arm.REGSP
		p = pp.Append(p, obj.ADUFFZERO, obj.TYPE_NONE, 0, 0, obj.TYPE_MEM, 0, 0)
		p.To.Name = obj.NAME_EXTERN
		p.To.Sym = ir.Syms.Duffzero
		p.To.Offset = 4 * (128 - cnt/int64(types.PtrSize))
	} else {
		p = pp.Append(p, arm.AADD, obj.TYPE_CONST, 0, 4+off, obj.TYPE_REG, arm.REG_R1, 0)
		p.Reg = arm.REGSP
		p = pp.Append(p, arm.AADD, obj.TYPE_CONST, 0, cnt, obj.TYPE_REG, arm.REG_R2, 0)
		p.Reg = arm.REG_R1
		p = pp.Append(p, arm.AMOVW, obj.TYPE_REG, arm.REG_R0, 0, obj.TYPE_MEM, arm.REG_R1, 4)
		p1 := p
		p.Scond |= arm.C_PBIT
		p = pp.Append(p, arm.ACMP, obj.TYPE_REG, arm.REG_R1, 0, obj.TYPE_NONE, 0, 0)
		p.Reg = arm.REG_R2
		p = pp.Append(p, arm.ABNE, obj.TYPE_NONE, 0, 0, obj.TYPE_BRANCH, 0, 0)
		p.To.SetTarget(p1)
	}

	return p
}

func ginsnop(pp *objw.Progs) *obj.Prog {
	p := pp.Prog(arm.AAND)
	p.From.Type = obj.TYPE_REG
	p.From.Reg = arm.REG_R0
	p.To.Type = obj.TYPE_REG
	p.To.Reg = arm.REG_R0
	p.Scond = arm.C_SCOND_EQ
	return p
}