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| author | Kartik Agaram <vc@akkartik.com> | 2021-01-13 16:57:04 -0800 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2021-01-13 16:57:04 -0800 |
| commit | ec0d5bb17e22e31c0edfc1b9b1e95ef363d690e7 (patch) | |
| tree | 0dd6b1dd1b9358f0e9495545bf6679f777706bbd /baremetal/501draw-text.mu | |
| parent | f6fd7e1be0780b5b6dee042bef1c4f0264069787 (diff) | |
| download | mu-ec0d5bb17e22e31c0edfc1b9b1e95ef363d690e7.tar.gz | |
7510 - baremetal: a game of snake
Diffstat (limited to 'baremetal/501draw-text.mu')
| -rw-r--r-- | baremetal/501draw-text.mu | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/baremetal/501draw-text.mu b/baremetal/501draw-text.mu index 5ddb4bf5..fa284d68 100644 --- a/baremetal/501draw-text.mu +++ b/baremetal/501draw-text.mu @@ -1,3 +1,64 @@ +# some primitives for moving the cursor without making assumptions about +# raster order +fn cursor-left screen: (addr screen) { + var cursor-x/eax: int <- copy 0 + var cursor-y/ecx: int <- copy 0 + cursor-x, cursor-y <- cursor-position screen + compare cursor-x, 0 + { + break-if-> + return + } + cursor-x <- subtract 8 # font-width + set-cursor-position screen, cursor-x, cursor-y +} + +fn cursor-right screen: (addr screen) { + var cursor-x/eax: int <- copy 0 + var cursor-y/ecx: int <- copy 0 + cursor-x, cursor-y <- cursor-position screen + compare cursor-x, 0x400 # screen-width + { + break-if-< + return + } + cursor-x <- add 8 # font-width + set-cursor-position screen, cursor-x, cursor-y +} + +fn cursor-up screen: (addr screen) { + var cursor-x/eax: int <- copy 0 + var cursor-y/ecx: int <- copy 0 + cursor-x, cursor-y <- cursor-position screen + compare cursor-y, 0 + { + break-if-> + return + } + cursor-y <- subtract 0x10 # screen-height + set-cursor-position screen, cursor-x, cursor-y +} + +fn cursor-down screen: (addr screen) { + var cursor-x/eax: int <- copy 0 + var cursor-y/ecx: int <- copy 0 + cursor-x, cursor-y <- cursor-position screen + compare cursor-y, 0x300 # screen-height + { + break-if-< + return + } + cursor-y <- add 0x10 # screen-height + set-cursor-position screen, cursor-x, cursor-y +} + +fn draw-grapheme-at-cursor screen: (addr screen), g: grapheme, color: int { + var cursor-x/eax: int <- copy 0 + var cursor-y/ecx: int <- copy 0 + cursor-x, cursor-y <- cursor-position screen + draw-grapheme screen, g, cursor-x, cursor-y, color +} + # draw a single line of text from x, y to xmax # return the next 'x' coordinate # if there isn't enough space, return 0 without modifying the screen |