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https://git.sr.ht/~rabbits/uxn
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Cleaned up ppu_read
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parent
c02dc5b0e2
commit
9de513ad47
2 changed files with 15 additions and 32 deletions
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@ -13,8 +13,9 @@ WITH REGARD TO THIS SOFTWARE.
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*/
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/*
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fgbg fgbg
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byte [0000 0000]
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pixel 0001 0002
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layer fgbg fgbg
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byte 1010 1010
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*/
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static Uint8 blending[5][16] = {
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@ -27,42 +28,25 @@ static Uint8 blending[5][16] = {
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static void
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ppu_clear(Ppu *p)
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{
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int x, y;
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for(y = 0; y < p->height; ++y) {
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for(x = 0; x < p->width; ++x) {
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ppu_write(p, 0, x, y, 0);
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ppu_write(p, 1, x, y, 0);
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}
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}
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int row;
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for(row = 0; row < p->height * p->width / 2; ++row)
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p->pixels[row] = 0;
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}
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Uint8
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ppu_read(Ppu *p, Uint16 x, Uint16 y)
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{
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int row = (x + y * p->width) / 0x2;
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if(x % 2) {
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if(p->pixels[row] & 0x0c) {
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return (p->pixels[row] >> 0x2) & 0x3;
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} else {
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return (p->pixels[row] >> 0x0) & 0x3;
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}
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} else {
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if(p->pixels[row] & 0xc0) {
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return (p->pixels[row] >> 0x6) & 0x3;
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} else {
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return (p->pixels[row] >> 0x4) & 0x3;
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}
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}
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return 0;
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Uint8 seg = !(x & 0x1) << 2;
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Uint8 byte = p->pixels[row] >> seg;
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return (byte & 0x0c ? (byte >> 2) : byte) & 0x3;
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}
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void
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ppu_write(Ppu *p, Uint8 layer, Uint16 x, Uint16 y, Uint8 color)
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{
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int row = (x + y * p->width) / 0x2;
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int original = p->pixels[row];
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Uint8 original = p->pixels[row];
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Uint8 next = 0x0;
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if(x % 2) {
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if(layer) {
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@ -82,7 +66,8 @@ ppu_write(Ppu *p, Uint8 layer, Uint16 x, Uint16 y, Uint8 color)
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}
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}
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p->pixels[row] = next;
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p->reqdraw = 1;
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if(original != next)
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p->reqdraw = 1;
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}
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void
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@ -127,9 +112,7 @@ ppu_set_size(Ppu *p, Uint16 width, Uint16 height)
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ppu_clear(p);
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p->width = width;
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p->height = height;
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p->pixels = realloc(p->bg, p->width * p->height * sizeof(Uint8) * 2);
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p->bg = p->pixels;
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p->fg = p->pixels + (p->width * p->height * sizeof(Uint8));
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p->pixels = realloc(p->pixels, p->width * p->height * sizeof(Uint8) / 2);
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ppu_clear(p);
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return p->bg && p->fg;
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return !!p->pixels;
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}
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@ -22,7 +22,7 @@ typedef unsigned short Uint16;
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typedef unsigned int Uint32;
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typedef struct Ppu {
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Uint8 *bg, *fg, *pixels, reqdraw;
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Uint8 *pixels, reqdraw;
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Uint16 width, height;
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} Ppu;
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