150 lines
7.5 KiB
Forth
150 lines
7.5 KiB
Forth
# Demo of combining-character support in Mu, which can be summarized as, "the
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# old typewriter-based approach of backing up one character and adding the
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# accent or _matra_ in."
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# https://en.wikipedia.org/wiki/Combining_character
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#
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# Mu uses this approach for both accents in Latin languages and vowel
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# diacritics in Abugida scripts.
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# https://en.wikipedia.org/wiki/Diacritic
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# https://en.wikipedia.org/wiki/Abugida
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#
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# Steps for trying it out:
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# 1. Translate this example into a disk image code.img.
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# ./translate apps/ex15.mu
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# 2. Run:
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# qemu-system-i386 -hda code.img -hdb data.img
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#
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# Expected output, showing off what this approach can and cannot do:
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# 'à' in green in a few places near the top-left corner of screen, with
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# other letters nearby showing cases where characters blend to the eye.
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#
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# A few Devanagari letter combinations. Devanagari works well except for
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# characters blending together.
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#
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# A few Tamil letter combinations. Tamil often doesn't look right, and
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# requires ligatures for many letter combinations.
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#
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# Others? (Patches welcome.) I suspect Tibetan in particular will not work
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# well with this approach. But I need native readers to assess quality.
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fn main screen: (addr screen), keyboard: (addr keyboard), data-disk: (addr disk) {
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# at the top of screen, the accent is almost cropped
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var dummy/eax: int <- draw-code-point-on-real-screen 0x61/a, 0/x 0/y, 3/fg 0/bg
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var dummy/eax: int <- overlay-code-point-on-real-screen 0x0300/combining-grave-accent, 0/x 0/y, 3/fg 0/bg
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# below a code-point-utf8 with a descender, the accent uglily overlaps
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# https://en.wikipedia.org/wiki/Descender
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var dummy/eax: int <- draw-code-point-on-real-screen 0x67/g, 4/x 3/y, 3/fg 0/bg
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var dummy/eax: int <- draw-code-point-on-real-screen 0x61/a, 4/x 4/y, 3/fg 0/bg
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var dummy/eax: int <- overlay-code-point-on-real-screen 0x0300/combining-grave-accent, 4/x 4/y, 3/fg 0/bg
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# beside a code-point-utf8 with a descender, it becomes more obvious that monowidth fonts can't make baselines line up
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# https://en.wikipedia.org/wiki/Baseline_(typography)
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var dummy/eax: int <- draw-code-point-on-real-screen 0x67/g, 8/x 3/y, 3/fg 0/bg
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var dummy/eax: int <- draw-code-point-on-real-screen 0x61/a, 9/x 3/y, 3/fg 0/bg
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var dummy/eax: int <- overlay-code-point-on-real-screen 0x0300/combining-grave-accent, 9/x 3/y, 3/fg 0/bg
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# a single devanagari letter combined with different vowel _matras_
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# ka
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var dummy/eax: int <- draw-code-point-on-real-screen 0x0915/devanagari-letter-ka, 4/x 8/y, 3/fg 0/bg
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# kaa
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var dummy/eax: int <- draw-code-point-on-real-screen 0x0915/devanagari-letter-ka, 7/x 8/y, 3/fg 0/bg
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var dummy/eax: int <- overlay-code-point-on-real-screen 0x093e/devanagari-vowel-aa, 7/x 8/y, 3/fg 0/bg
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# ki
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var dummy/eax: int <- draw-code-point-on-real-screen 0x0915/devanagari-letter-ka, 0xa/x 8/y, 3/fg 0/bg
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var dummy/eax: int <- overlay-code-point-on-real-screen 0x093f/devanagari-vowel-i, 0xa/x 8/y, 3/fg 0/bg
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# kee
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var dummy/eax: int <- draw-code-point-on-real-screen 0x0915/devanagari-letter-ka, 0xd/x 8/y, 3/fg 0/bg
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var dummy/eax: int <- overlay-code-point-on-real-screen 0x0940/devanagari-vowel-ii, 0xd/x 8/y, 3/fg 0/bg
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# ku
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var dummy/eax: int <- draw-code-point-on-real-screen 0x0915/devanagari-letter-ka, 0x10/x 8/y, 3/fg 0/bg
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var dummy/eax: int <- overlay-code-point-on-real-screen 0x0941/devanagari-vowel-u, 0x10/x 8/y, 3/fg 0/bg
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# koo
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var dummy/eax: int <- draw-code-point-on-real-screen 0x0915/devanagari-letter-ka, 0x13/x 8/y, 3/fg 0/bg
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var dummy/eax: int <- overlay-code-point-on-real-screen 0x0942/devanagari-vowel-oo, 0x13/x 8/y, 3/fg 0/bg
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# kay
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var dummy/eax: int <- draw-code-point-on-real-screen 0x0915/devanagari-letter-ka, 4/x 9/y, 3/fg 0/bg
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var dummy/eax: int <- overlay-code-point-on-real-screen 0x0947/devanagari-vowel-E, 4/x 9/y, 3/fg 0/bg
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# kai
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var dummy/eax: int <- draw-code-point-on-real-screen 0x0915/devanagari-letter-ka, 7/x 9/y, 3/fg 0/bg
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var dummy/eax: int <- overlay-code-point-on-real-screen 0x0948/devanagari-vowel-ai, 7/x 9/y, 3/fg 0/bg
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# ko
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var dummy/eax: int <- draw-code-point-on-real-screen 0x0915/devanagari-letter-ka, 0xa/x 9/y, 3/fg 0/bg
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var dummy/eax: int <- overlay-code-point-on-real-screen 0x094b/devanagari-vowel-o, 0xa/x 9/y, 3/fg 0/bg
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# kow
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var dummy/eax: int <- draw-code-point-on-real-screen 0x0915/devanagari-letter-ka, 0xd/x 9/y, 3/fg 0/bg
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var dummy/eax: int <- overlay-code-point-on-real-screen 0x094f/devanagari-vowel-aw, 0xd/x 9/y, 3/fg 0/bg
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# kan
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# bump this letter down to show the letter without overlap; we've already established above that overlap is an issue
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var dummy/eax: int <- draw-code-point-on-real-screen 0x0915/devanagari-letter-ka, 0x10/x 0xa/y, 3/fg 0/bg
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var dummy/eax: int <- overlay-code-point-on-real-screen 0x0902/devanagari-anusvara, 0x10/x 0xa/y, 3/fg 0/bg
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# kaha
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var dummy/eax: int <- draw-code-point-on-real-screen 0x0915/devanagari-letter-ka, 0x13/x 9/y, 3/fg 0/bg
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var dummy/eax: int <- overlay-code-point-on-real-screen 0x0903/devanagari-visarga, 0x13/x 9/y, 3/fg 0/bg
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# render the same devanagari letters as a single stream of utf-8 code-point-utf8s rather than individual code-points.
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var text-storage: (stream byte 0x200)
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var text/esi: (addr stream byte) <- address text-storage
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var g/eax: code-point-utf8 <- to-utf8 0x0915/devanagari-letter-ka
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var ka/ecx: code-point-utf8 <- copy g
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# ka
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write-code-point-utf8 text, ka
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# kaa
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write-code-point-utf8 text, ka
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g <- to-utf8 0x093e/devanagari-vowel-aa
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write-code-point-utf8 text, g
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# ki
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write-code-point-utf8 text, ka
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g <- to-utf8 0x093f/devanagari-vowel-i
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write-code-point-utf8 text, g
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# kee
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write-code-point-utf8 text, ka
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g <- to-utf8 0x0940/devanagari-vowel-ii
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write-code-point-utf8 text, g
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# ku
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write-code-point-utf8 text, ka
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g <- to-utf8 0x0941/devanagari-vowel-u
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write-code-point-utf8 text, g
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# koo
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write-code-point-utf8 text, ka
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g <- to-utf8 0x0942/devanagari-vowel-oo
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write-code-point-utf8 text, g
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# kay
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write-code-point-utf8 text, ka
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g <- to-utf8 0x0947/devanagari-vowel-E
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write-code-point-utf8 text, g
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# kai
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write-code-point-utf8 text, ka
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g <- to-utf8 0x0948/devanagari-vowel-ai
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write-code-point-utf8 text, g
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# ko
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write-code-point-utf8 text, ka
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g <- to-utf8 0x094b/devanagari-vowel-o
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write-code-point-utf8 text, g
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# kow
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write-code-point-utf8 text, ka
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g <- to-utf8 0x094f/devanagari-vowel-aw
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write-code-point-utf8 text, g
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# kan
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write-code-point-utf8 text, ka
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g <- to-utf8 0x0902/devanagari-anusvara
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write-code-point-utf8 text, g
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# kaha
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write-code-point-utf8 text, ka
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g <- to-utf8 0x0903/devanagari-visarga
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write-code-point-utf8 text, g
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# render everything
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set-cursor-position screen, 4/x 0xe/y
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draw-stream-wrapping-right-then-down-from-cursor-over-full-screen screen, text, 3/fg 0/bg
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# a stream of tamil code-point-utf8s (with interspersed spaces for clarity) that don't look the same in Mu
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set-cursor-position 0, 4/x 0x12/y
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draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0, "எ ஃ கு ", 3/fg 0/bg
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set-cursor-position 0, 4/x 0x13/y
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draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0, "அ ன் று ", 3/fg 0/bg
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set-cursor-position 0, 4/x 0x14/y
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draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0, "அ தா வ து " , 3/fg 0/bg
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set-cursor-position 0, 4/x 0x15/y
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draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0, "அ ஃ தா ன் று ", 3/fg 0/bg
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}
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