forked from AbleOS/ableos
88 lines
2.7 KiB
Plaintext
88 lines
2.7 KiB
Plaintext
.{memory, math} := @use("../../../libraries/stn/src/lib.hb");
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.{ColorBGRA, blend} := @use("rel:color.hb")
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FB_WIDTH := 1024
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FB_HEIGHT := 768
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FB_PIXELS := FB_WIDTH * FB_HEIGHT
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FB_BYTES := FB_PIXELS << 2
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// actual enforced max copy size is 0xFFFF, but this was faster
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MAX_COPY_SIZE := 0x1800
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COPY_PIXELS := math.min(MAX_COPY_SIZE, FB_BYTES) >> 2
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PARTITIONS := FB_PIXELS / COPY_PIXELS
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TOTAL_PAGES := 1 + FB_BYTES >> 12
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Buffer := struct {write: ^ColorBGRA, copy: ^[ColorBGRA; COPY_PIXELS]}
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Point := struct {x: int, y: int}
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Transform := struct {width: int, height: int}
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front_buffer_ptr := @as(^ColorBGRA, @bitcast(0xFFFF8000C0000000))
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front_buffer_copy := @as(^[ColorBGRA; COPY_PIXELS], @bitcast(front_buffer_ptr))
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get_front_buffer := fn(): Buffer {
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// trying to return front_buffer_ptr or front_buffer_copy causes reg id leak
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buffer := Buffer.{write: front_buffer_ptr, copy: front_buffer_copy}
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return buffer
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}
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/* this is separate to create_raw_buffer because returning a Buffer from
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create_raw_buffer causes reg id leak */
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create_buffer := fn(): Buffer {
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ptr := @inline(create_raw_buffer)
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buffer := Buffer.{write: ptr, copy: @as(^[ColorBGRA; COPY_PIXELS], @bitcast(ptr))}
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return buffer
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}
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create_raw_buffer := fn(): ^ColorBGRA {
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if TOTAL_PAGES <= 0xFF {
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return @bitcast(@inline(memory.request_page, TOTAL_PAGES))
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}
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ptr := @inline(memory.request_page, 255)
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remaining := TOTAL_PAGES - 0xFF
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loop if remaining <= 0 break else {
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if remaining < 0xFF {
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memory.request_page(remaining)
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} else {
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memory.request_page(0xFF)
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}
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remaining -= 0xFF
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}
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return @bitcast(ptr)
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}
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// sets the buffer to the color. very fast.
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clear := fn(buffer: Buffer, color: ColorBGRA): void {
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n := 0
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// write the first pixel chunk
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loop if n >= COPY_PIXELS break else {
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*(buffer.write + n) = color
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n += 1
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}
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n = 1
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// copy that pixel chunk through the buffer, taking advantage of memory copying
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loop if n >= PARTITIONS break else {
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*(buffer.copy + n) = *buffer.copy
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n += 1
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}
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return
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}
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// only required to be called when using a back buffer. if using single-buffered rendering, do not call this.
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present := fn(buffer: Buffer): void {
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n := 0
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// copy chunks of the read buffer to the front buffer
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loop if n >= PARTITIONS break else {
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*(front_buffer_copy + n) = *(buffer.copy + n)
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n += 1
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}
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return
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}
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// composites the contents of buffer1 into buffer2, accounting for alpha transparency
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// i dont know if it works. i have not tested it. it probably doesnt work
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composite := fn(buffer1: Buffer, buffer2: Buffer): void {
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n := 0
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loop if n == FB_PIXELS break else {
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bg := *(buffer2.write + n);
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*(buffer2.write + n) = blend(*(buffer1.write + n), bg)
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n += 1
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}
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return
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}
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screenidx := fn(pos: Point): int {
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return pos.x + FB_WIDTH * pos.y
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} |