fn draw-line screen: (addr screen), x0: int, y0: int, x1: int, y1: int, color: int {
var dx: int
var dy: int
var sx: int
var sy: int
var err: int
# dx = abs(x1-x0)
var tmp2/ecx: int <- copy x1
tmp2 <- subtract x0
var tmp/eax: int <- abs tmp2
copy-to dx, tmp
# sx = sgn(x1-x0)
tmp <- sgn tmp2
copy-to sx, tmp
# dy = -abs(y1-y0)
tmp2 <- copy y1
tmp2 <- subtract y0
tmp <- abs tmp2
tmp <- negate
copy-to dy, tmp
# sy = sgn(y1-y0)
tmp <- sgn tmp2
copy-to sy, tmp
# err = dx + dy
tmp <- copy dy
tmp <- add dx
copy-to err, tmp
#
var x/ecx: int <- copy x0
var y/edx: int <- copy y0
$draw-line:loop: {
pixel screen, x, y, color
# if (x == x1 && y == y1) break
{
compare x, x1
break-if-!=
compare y, y1
break-if-!=
break $draw-line:loop
}
# e2 = err*2
var e2/ebx: int <- copy err
e2 <- shift-left 1
# if (e2 >= dy) { err += dy; x += sx; }
{
compare e2, dy
break-if-<
tmp <- copy dy
add-to err, tmp
x <- add sx
}
# if (e2 <= dx) { err += dx; y += sy; }
{
compare e2, dx
break-if->
tmp <- copy dx
add-to err, tmp
y <- add sy
}
loop
}
}
fn draw-horizontal-line screen: (addr screen), y: int, x0: int, x1: int, color: int {
var x/eax: int <- copy x0
{
compare x, x1
break-if->=
pixel screen, x, y, color
x <- increment
loop
}
}
fn draw-vertical-line screen: (addr screen), x: int, y0: int, y1: int, color: int {
var y/eax: int <- copy y0
{
compare y, y1
break-if->=
pixel screen, x, y, color
y <- increment
loop
}
}
fn draw-rect screen: (addr screen), xmin: int, ymin: int, xmax: int, ymax: int, color: int {
var y/eax: int <- copy ymin
{
compare y, ymax
break-if->=
draw-horizontal-line screen, y, xmin, xmax, color
y <- increment
loop
}
}
# 0 <= u <= 1
fn line-point u: float, x0: int, x1: int -> _/eax: int {
var one/eax: int <- copy 1
var u-prime/xmm0: float <- convert one
u-prime <- subtract u
var result/xmm1: float <- convert x0
result <- multiply u-prime
var term2/xmm2: float <- convert x1
term2 <- multiply u
result <- add term2
var result/eax: int <- convert result
return result
}