Matrix Rain: 2025 refactor

MATRIX RAIN: 2025 REFACTOR

21 DECEMBER 2025

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The 2022 version worked but had some loose ends. Unicode support was -inflexible–couldn’t mix ASCII with Katakana; Phosphor decay was stored in a -separate array when it should’ve been packed with RGB; Code was harder to read -than it needed to be.

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Moved phosphor decay into the 4th byte of the RGB union–should’ve done this -in 2022; What was I thinking.

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Keeping the RGB union despite portability concerns. All my systems are -little-endian and the code is cleaner this way.

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Fixed Unicode by introducing a charset array. UNICODE(min, max) packs Unicode -ranges into uint64: low four bytes for start, high four bytes for end. -insert_code() unpacks a random block and picks a character from it:

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#define UNICODE(min, max)  (((uint64_t)max << 32) | min)
-
-static uint64_t glyphs[] = {
-    UNICODE(0x0021, 0x007E), /* ASCII */
-    UNICODE(0xFF65, 0xFF9F), /* Half-width Katakana */
-};
-
-static inline void insert_code(matrix *mat,
-    size_t row, size_t col) 
-{
-    uint64_t blk;
-    uint32_t min, max;
-
-    blk = glyphs[(rand() % glyphlen)];
-    min = (uint32_t)blk;
-    max = (uint32_t)(blk >> 32);
-    mat->code[index(mat, row, col)] = rand() % (max - min) + min;
-}
-

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Full-width Katakana breaks column alignment. Stick to half-width -(U+FF61-U+FF9F) range. Compile with -DNOKANA to disable Katakana altogether.

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blend() is still good. Leaving it alone.

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Tossed license and automake cruft. Just cc -O3 main.c -o matrix now. Don’t -need the ceremony.

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Runs at 2-3% CPU on OpenBSD (T490). No regressions. Fans are quiet.

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Commit: f71b0de.

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by W. D. Sadeep Madurange