func NewParser() *Parser {
self := new(Parser)
self.prog = asm.NewProg()
self.errors = make([]error, 0, 1024)
return self
}
func p0() *asm.Prog {
p := asm.NewProg()
/*
argument <- base stack pointer
return value
return pc <- call1 stack pointer
sum tmp
argument
return value
return pc <- call2 stack pointer
*/
arg := int32(4)
f := p.F("main")
f.Addi(14, 0, int32(vm.PageStart(2)))
f.Addi(1, 0, arg)
f.Sd(1, 14, 0) // argument for calling
f.Addi(14, 14, 16) // prepare stack for calling
f.Jal("fab")
f.Ld(1, 14, -8) // fetch return value
f.Addi(14, 14, -16) // restore stack from calling
f.Halt()
f = p.F("fab")
f.Sd(15, 14, 0) // store pc pointer
f.Ld(1, 14, -16) // load the argument
f.Beq(1, 0, "ret1") // fab(0)
f.Addi(1, 1, -1) // $2 = arg - 1
f.Beq(1, 0, "ret1") // fab(1)
// sub call fab(arg-1)
f.Sd(1, 14, 16) // argument for calling
f.Addi(14, 14, 32) // prepare stack for calling
f.Jal("fab")
f.Ld(2, 14, -8) // fetch return value
f.Addi(14, 14, -32) // restore stack from calling
f.Sd(2, 14, 8) // save return value
// sub call fab(arg-2)
f.Ld(1, 14, -16) // load the argument again
f.Addi(1, 1, -2) // $3 = arg - 2
f.Sd(1, 14, 16) // argument for calling
f.Addi(14, 14, 32) // prepare stack for calling
f.Jal("fab")
f.Ld(2, 14, -8) // fetch return value
f.Addi(14, 14, -32) // retore stack from calling
f.Ld(1, 14, 8) // load tmp
f.Add(1, 1, 2)
f.Beq(0, 0, "out") // jump to out
f.L("ret1")
f.Addi(1, 0, 1) // set 1 to 1
f.L("out")
f.Sd(1, 14, -8) // return 1
f.Ld(15, 14, 0) // restore pc
f.Jr(15) // return
return p
}