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Bare metal VGA: fix mapping of ECMA-48 colors to VGA colors (#622)

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See https://github.com/jart/cosmopolitan/pull/613#issuecomment-1247490693
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tkchia 2022-09-18 17:50:00 +08:00 • committed by GitHub
parent 4c40c500b8
commit cdf9e8c8a3
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1 changed files with 32 additions and 2 deletions
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34
libc/vga/tty.c
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@ -605,6 +605,36 @@ static void TtyCsiN(struct Tty *tty) {
}
}
/**
* Map the given ECMA-48 / VT100 SGR color code to a color code for a VGA
* character attribute. More precisely, map
*
* red──┐
* green─┐│
* blue┐││
* intensity│││
* ││││
* 3210
*
* to
*
* blue──┐
* green─┐│
* red┐││
* intensity│││
* ││││
* 3210
*/
static uint8_t TtyMapEcma48Color(uint8_t color)
{
switch (color & 0b101) {
case 0b100:
case 0b001:
color ^= 0b101;
}
return color;
}
/**
* Map the given (R, G, B) triplet to one of the 16 basic foreground colors
* or one of the 16 background colors.
@ -765,7 +795,7 @@ static void TtySelectGraphicsRendition(struct Tty *tty) {
code[0] += 8;
/* fallthrough */
case 30 ... 37:
tty->fg = code[0] - 30;
tty->fg = TtyMapEcma48Color(code[0] - 30);
tty->pr |= kTtyFg;
tty->pr &= ~kTtyTrue;
break;
@ -774,7 +804,7 @@ static void TtySelectGraphicsRendition(struct Tty *tty) {
code[0] += 8;
/* fallthrough */
case 40 ... 47:
tty->bg = code[0] - 40;
tty->bg = TtyMapEcma48Color(code[0] - 40);
tty->pr |= kTtyBg;
tty->pr &= ~kTtyTrue;
break;