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# slow, iterative divide instruction
# preconditions: _nr >= 0, _dr > 0
fn try-divide _nr: int, _dr: int -> _/eax: int {
# x = next power-of-2 multiple of _dr after _nr
var x/ecx: int <- copy 1
{
#? print-int32-hex 0, x
#? print-string 0, "\n"
var tmp/edx: int <- copy _dr
tmp <- multiply x
compare tmp, _nr
break-if->
x <- shift-left 1
loop
}
#? print-string 0, "--\n"
# min, max = x/2, x
var max/ecx: int <- copy x
var min/edx: int <- copy max
min <- shift-right 1
# narrow down result between min and max
var i/eax: int <- copy min
{
#? print-int32-hex 0, i
#? print-string 0, "\n"
var foo/ebx: int <- copy _dr
foo <- multiply i
compare foo, _nr
break-if->
i <- increment
loop
}
var result/eax: int <- copy i
result <- decrement
#? print-string 0, "=> "
#? print-int32-hex 0, result
#? print-string 0, "\n"
return result
}
fn test-try-divide-1 {
var result/eax: int <- try-divide 0, 2
check-ints-equal result, 0, "F - try-divide-1"
}
fn test-try-divide-2 {
var result/eax: int <- try-divide 1, 2
check-ints-equal result, 0, "F - try-divide-2"
}
fn test-try-divide-3 {
var result/eax: int <- try-divide 2, 2
check-ints-equal result, 1, "F - try-divide-3"
}
fn test-try-divide-4 {
var result/eax: int <- try-divide 4, 2
check-ints-equal result, 2, "F - try-divide-4"
}
fn test-try-divide-5 {
var result/eax: int <- try-divide 6, 2
check-ints-equal result, 3, "F - try-divide-5"
}
fn test-try-divide-6 {
var result/eax: int <- try-divide 9, 3
check-ints-equal result, 3, "F - try-divide-6"
}
fn test-try-divide-7 {
var result/eax: int <- try-divide 0xc, 4
check-ints-equal result, 3, "F - try-divide-7"
}
fn test-try-divide-8 {
var result/eax: int <- try-divide 0x1b, 3 # 27/3
check-ints-equal result, 9, "F - try-divide-8"
}
fn test-try-divide-9 {
var result/eax: int <- try-divide 0x1c, 3 # 28/3
check-ints-equal result, 9, "F - try-divide-9"
}
# only positive dr for now
fn try-modulo nr: int, dr: int -> _/eax: int {
var _positive-nr/eax: int <- abs nr
var positive-nr/ecx: int <- copy _positive-nr
var result/eax: int <- try-divide positive-nr, dr
result <- multiply dr
result <- subtract positive-nr
result <- negate
return result
}
fn test-try-modulo-negative-nr {
var result/eax: int <- try-modulo -0xa, 7
check-ints-equal result, 3, "F - test-try-modulo-negative-nr"
}
# slow, iterative shift-left instruction
# preconditions: _nr >= 0, _dr > 0
fn repeated-shift-left nr: int, dr: int -> _/eax: int {
var result/eax: int <- copy nr
{
compare dr, 0
break-if-<=
result <- shift-left 1
decrement dr
loop
}
return result
}
# slow, iterative shift-right instruction
# preconditions: _nr >= 0, _dr > 0
fn repeated-shift-right nr: int, dr: int -> _/eax: int {
var result/eax: int <- copy nr
{
compare dr, 0
break-if-<=
result <- shift-right 1
decrement dr
loop
}
return result
}
fn abs n: int -> _/eax: int {
var result/eax: int <- copy n
{
compare n, 0
break-if->=
result <- negate
}
return result
}
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