118 lines
2.5 KiB
Forth
118 lines
2.5 KiB
Forth
fn draw-line screen: (addr screen), x0: int, y0: int, x1: int, y1: int, color: int {
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var dx: int
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var dy: int
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var sx: int
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var sy: int
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var err: int
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# dx = abs(x1-x0)
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var tmp2/ecx: int <- copy x1
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tmp2 <- subtract x0
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var tmp/eax: int <- abs tmp2
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copy-to dx, tmp
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# sx = sgn(x1-x0)
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tmp <- sgn tmp2
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copy-to sx, tmp
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# dy = -abs(y1-y0)
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tmp2 <- copy y1
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tmp2 <- subtract y0
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tmp <- abs tmp2
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tmp <- negate
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copy-to dy, tmp
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# sy = sgn(y1-y0)
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tmp <- sgn tmp2
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copy-to sy, tmp
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# err = dx + dy
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tmp <- copy dy
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tmp <- add dx
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copy-to err, tmp
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#
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var x/ecx: int <- copy x0
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var y/edx: int <- copy y0
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$draw-line:loop: {
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pixel screen, x, y, color
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# if (x == x1 && y == y1) break
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{
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compare x, x1
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break-if-!=
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compare y, y1
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break-if-!=
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break $draw-line:loop
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}
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# e2 = err*2
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var e2/ebx: int <- copy err
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e2 <- shift-left 1
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# if (e2 >= dy) { err += dy; x += sx; }
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{
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compare e2, dy
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break-if-<
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tmp <- copy dy
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add-to err, tmp
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x <- add sx
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}
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# if (e2 <= dx) { err += dx; y += sy; }
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{
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compare e2, dx
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break-if->
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tmp <- copy dx
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add-to err, tmp
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y <- add sy
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}
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loop
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}
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}
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fn draw-horizontal-line screen: (addr screen), y: int, x0: int, x1: int, color: int {
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var x/eax: int <- copy x0
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{
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compare x, x1
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break-if->=
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pixel screen, x, y, color
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x <- increment
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loop
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}
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}
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fn draw-vertical-line screen: (addr screen), x: int, y0: int, y1: int, color: int {
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var y/eax: int <- copy y0
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{
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compare y, y1
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break-if->=
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pixel screen, x, y, color
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y <- increment
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loop
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}
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}
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fn draw-rect screen: (addr screen), xmin: int, ymin: int, xmax: int, ymax: int, color: int {
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var y/eax: int <- copy ymin
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{
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compare y, ymax
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break-if->=
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draw-horizontal-line screen, y, xmin, xmax, color
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y <- increment
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loop
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}
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}
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fn draw-rect2 screen: (addr screen), xmin: int, ymin: int, w: int, h: int, color: int {
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var xmax/eax: int <- copy xmin
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xmax <- add w
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var ymax/ecx: int <- copy ymin
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ymax <- add h
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draw-rect screen, xmin ymin, xmax ymax, color
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}
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# 0 <= u <= 1
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fn line-point u: float, x0: int, x1: int -> _/eax: int {
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var one/eax: int <- copy 1
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var u-prime/xmm0: float <- convert one
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u-prime <- subtract u
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var result/xmm1: float <- convert x0
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result <- multiply u-prime
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var term2/xmm2: float <- convert x1
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term2 <- multiply u
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result <- add term2
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var result/eax: int <- convert result
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return result
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}
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