fix 6-bit to 8-bit palette conversion
this now produces "full range" results, e.g. VGA color 15 (bright white) now converts to 255,255,255 instead of 252,252,252.
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@ -1,22 +1,21 @@
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// these colours are taken from the default VGA palette with a simple conversion from their original
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// 0-63 range to 0-255.
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// these colours are taken from the default VGA palette
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pub const COLOR_BLACK: u32 = 0xff000000;
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pub const COLOR_BLUE: u32 = 0xff0000a8;
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pub const COLOR_GREEN: u32 = 0xff00a800;
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pub const COLOR_CYAN: u32 = 0xff00a8a8;
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pub const COLOR_RED: u32 = 0xffa80000;
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pub const COLOR_MAGENTA: u32 = 0xffa800a8;
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pub const COLOR_BROWN: u32 = 0xffa85400;
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pub const COLOR_LIGHT_GRAY: u32 = 0xffa8a8a8;
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pub const COLOR_DARK_GRAY: u32 = 0xff545454;
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pub const COLOR_BRIGHT_BLUE: u32 = 0xff5454fc;
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pub const COLOR_BRIGHT_GREEN: u32 = 0xff54fc54;
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pub const COLOR_BRIGHT_CYAN: u32 = 0xff54fcfc;
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pub const COLOR_BRIGHT_RED: u32 = 0xfffc5454;
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pub const COLOR_BRIGHT_MAGENTA: u32 = 0xfffc54fc;
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pub const COLOR_BRIGHT_YELLOW: u32 = 0xfffcfc54;
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pub const COLOR_BRIGHT_WHITE: u32 = 0xfffcfcfc;
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pub const COLOR_BLUE: u32 = 0xff0000aa;
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pub const COLOR_GREEN: u32 = 0xff00aa00;
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pub const COLOR_CYAN: u32 = 0xff00aaaa;
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pub const COLOR_RED: u32 = 0xffaa0000;
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pub const COLOR_MAGENTA: u32 = 0xffaa00aa;
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pub const COLOR_BROWN: u32 = 0xffaa5500;
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pub const COLOR_LIGHT_GRAY: u32 = 0xffaaaaaa;
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pub const COLOR_DARK_GRAY: u32 = 0xff555555;
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pub const COLOR_BRIGHT_BLUE: u32 = 0xff5555ff;
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pub const COLOR_BRIGHT_GREEN: u32 = 0xff55ff55;
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pub const COLOR_BRIGHT_CYAN: u32 = 0xff55ffff;
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pub const COLOR_BRIGHT_RED: u32 = 0xffff5555;
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pub const COLOR_BRIGHT_MAGENTA: u32 = 0xffff55ff;
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pub const COLOR_BRIGHT_YELLOW: u32 = 0xffffff55;
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pub const COLOR_BRIGHT_WHITE: u32 = 0xffffffff;
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/// Converts a set of individual ARGB components to a combined 32-bit color value, packed into
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/// the format 0xAARRGGBB
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@ -18,6 +18,16 @@ impl<T> ColorRange for T where T: RangeBounds<u8> + Iterator<Item=u8> {}
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pub static VGA_PALETTE_BYTES: &[u8] = include_bytes!("../../assets/vga.pal");
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#[inline]
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fn from_6bit(value: u8) -> u8 {
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(value.wrapping_shl(2) | value.wrapping_shr(4)) as u8
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}
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#[inline]
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fn to_6bit(value: u8) -> u8 {
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(value.wrapping_shr(2)) as u8
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}
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// vga bios (0-63) format
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fn read_palette_6bit<T: ReadBytesExt>(
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reader: &mut T,
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@ -31,7 +41,11 @@ fn read_palette_6bit<T: ReadBytesExt>(
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let r = reader.read_u8()?;
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let g = reader.read_u8()?;
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let b = reader.read_u8()?;
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let color = to_rgb32(r * 4, g * 4, b * 4);
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let color = to_rgb32(
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from_6bit(r),
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from_6bit(g),
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from_6bit(b)
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);
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colors[i as usize] = color;
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}
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Ok(colors)
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@ -47,9 +61,9 @@ fn write_palette_6bit<T: WriteBytesExt>(
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}
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for i in 0..num_colors {
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let (r, g, b) = from_rgb32(colors[i as usize]);
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writer.write_u8(r / 4)?;
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writer.write_u8(g / 4)?;
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writer.write_u8(b / 4)?;
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writer.write_u8(to_6bit(r))?;
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writer.write_u8(to_6bit(g))?;
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writer.write_u8(to_6bit(b))?;
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}
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Ok(())
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}
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@ -517,7 +531,7 @@ mod tests {
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use tempfile::TempDir;
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use crate::graphics::color::{from_argb32, to_argb32};
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use crate::graphics::color::*;
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use super::*;
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@ -558,22 +572,22 @@ mod tests {
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}
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fn assert_ega_colors(palette: &Palette) {
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assert_eq!(0xff000000, palette[0]);
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assert_eq!(0xff0000a8, palette[1]);
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assert_eq!(0xff00a800, palette[2]);
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assert_eq!(0xff00a8a8, palette[3]);
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assert_eq!(0xffa80000, palette[4]);
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assert_eq!(0xffa800a8, palette[5]);
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assert_eq!(0xffa85400, palette[6]);
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assert_eq!(0xffa8a8a8, palette[7]);
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assert_eq!(0xff545454, palette[8]);
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assert_eq!(0xff5454fc, palette[9]);
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assert_eq!(0xff54fc54, palette[10]);
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assert_eq!(0xff54fcfc, palette[11]);
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assert_eq!(0xfffc5454, palette[12]);
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assert_eq!(0xfffc54fc, palette[13]);
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assert_eq!(0xfffcfc54, palette[14]);
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assert_eq!(0xfffcfcfc, palette[15]);
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assert_eq!(COLOR_BLACK, palette[0]);
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assert_eq!(COLOR_BLUE, palette[1]);
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assert_eq!(COLOR_GREEN, palette[2]);
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assert_eq!(COLOR_CYAN, palette[3]);
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assert_eq!(COLOR_RED, palette[4]);
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assert_eq!(COLOR_MAGENTA, palette[5]);
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assert_eq!(COLOR_BROWN, palette[6]);
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assert_eq!(COLOR_LIGHT_GRAY, palette[7]);
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assert_eq!(COLOR_DARK_GRAY, palette[8]);
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assert_eq!(COLOR_BRIGHT_BLUE, palette[9]);
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assert_eq!(COLOR_BRIGHT_GREEN, palette[10]);
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assert_eq!(COLOR_BRIGHT_CYAN, palette[11]);
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assert_eq!(COLOR_BRIGHT_RED, palette[12]);
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assert_eq!(COLOR_BRIGHT_MAGENTA, palette[13]);
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assert_eq!(COLOR_BRIGHT_YELLOW, palette[14]);
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assert_eq!(COLOR_BRIGHT_WHITE, palette[15]);
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}
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#[test]
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