151 lines
4.5 KiB
C
151 lines
4.5 KiB
C
#include "ppu.h"
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/*
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Copyright (c) 2021 Devine Lu Linvega
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Copyright (c) 2021 Andrew Alderwick
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Permission to use, copy, modify, and distribute this software for any
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purpose with or without fee is hereby granted, provided that the above
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copyright notice and this permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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WITH REGARD TO THIS SOFTWARE.
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*/
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static Uint8 blending[5][16] = {
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{0, 0, 0, 0, 1, 0, 1, 1, 2, 2, 0, 2, 3, 3, 3, 0},
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{0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3},
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{1, 2, 3, 1, 1, 2, 3, 1, 1, 2, 3, 1, 1, 2, 3, 1},
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{2, 3, 1, 2, 2, 3, 1, 2, 2, 3, 1, 2, 2, 3, 1, 2},
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{1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0}};
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static Uint8 font[][8] = {
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{0x00, 0x7c, 0x82, 0x82, 0x82, 0x82, 0x82, 0x7c},
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{0x00, 0x30, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10},
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{0x00, 0x7c, 0x82, 0x02, 0x7c, 0x80, 0x80, 0xfe},
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{0x00, 0x7c, 0x82, 0x02, 0x1c, 0x02, 0x82, 0x7c},
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{0x00, 0x0c, 0x14, 0x24, 0x44, 0x84, 0xfe, 0x04},
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{0x00, 0xfe, 0x80, 0x80, 0x7c, 0x02, 0x82, 0x7c},
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{0x00, 0x7c, 0x82, 0x80, 0xfc, 0x82, 0x82, 0x7c},
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{0x00, 0x7c, 0x82, 0x02, 0x1e, 0x02, 0x02, 0x02},
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{0x00, 0x7c, 0x82, 0x82, 0x7c, 0x82, 0x82, 0x7c},
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{0x00, 0x7c, 0x82, 0x82, 0x7e, 0x02, 0x82, 0x7c},
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{0x00, 0x7c, 0x82, 0x02, 0x7e, 0x82, 0x82, 0x7e},
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{0x00, 0xfc, 0x82, 0x82, 0xfc, 0x82, 0x82, 0xfc},
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{0x00, 0x7c, 0x82, 0x80, 0x80, 0x80, 0x82, 0x7c},
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{0x00, 0xfc, 0x82, 0x82, 0x82, 0x82, 0x82, 0xfc},
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{0x00, 0x7c, 0x82, 0x80, 0xf0, 0x80, 0x82, 0x7c},
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{0x00, 0x7c, 0x82, 0x80, 0xf0, 0x80, 0x80, 0x80}};
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void
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ppu_palette(Ppu *p, Uint8 *addr)
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{
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int i, shift;
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for(i = 0, shift = 4; i < 4; ++i, shift ^= 4) {
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Uint8
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r = (addr[0 + i / 2] >> shift) & 0x0f,
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g = (addr[2 + i / 2] >> shift) & 0x0f,
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b = (addr[4 + i / 2] >> shift) & 0x0f;
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p->palette[i] = 0x0f000000 | r << 16 | g << 8 | b;
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p->palette[i] |= p->palette[i] << 4;
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}
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p->fg.changed = p->bg.changed = 1;
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}
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void
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ppu_resize(Ppu *p, Uint16 width, Uint16 height)
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{
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Uint8
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*bg = realloc(p->bg.pixels, width * height),
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*fg = realloc(p->fg.pixels, width * height);
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if(bg) p->bg.pixels = bg;
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if(fg) p->fg.pixels = fg;
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if(bg && fg) {
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p->width = width;
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p->height = height;
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ppu_clear(p, &p->bg);
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ppu_clear(p, &p->fg);
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}
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}
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void
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ppu_clear(Ppu *p, Layer *layer)
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{
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Uint32 i, size = p->width * p->height;
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for(i = 0; i < size; ++i)
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layer->pixels[i] = 0x00;
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layer->changed = 1;
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}
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#pragma weak ppu_redraw
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void
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ppu_redraw(Ppu *p, Uint32 *screen)
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{
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Uint32 i, size = p->width * p->height, palette[16];
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for(i = 0; i < 16; ++i)
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palette[i] = p->palette[(i >> 2) ? (i >> 2) : (i & 3)];
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for(i = 0; i < size; ++i)
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screen[i] = palette[p->fg.pixels[i] << 2 | p->bg.pixels[i]];
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p->fg.changed = p->bg.changed = 0;
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}
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void
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ppu_write(Ppu *p, Layer *layer, Uint16 x, Uint16 y, Uint8 color)
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{
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if(x < p->width && y < p->height) {
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Uint32 i = x + y * p->width;
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Uint8 prev = layer->pixels[i];
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if(color != prev) {
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layer->pixels[i] = color;
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layer->changed = 1;
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}
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}
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}
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void
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ppu_blit(Ppu *p, Layer *layer, Uint16 x, Uint16 y, Uint8 *sprite, Uint8 color, Uint8 flipx, Uint8 flipy, Uint8 twobpp)
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{
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int v, h, opaque = blending[4][color];
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for(v = 0; v < 8; ++v) {
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Uint16 c = sprite[v] | (twobpp ? sprite[v + 8] : 0) << 8;
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for(h = 7; h >= 0; --h, c >>= 1) {
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Uint8 ch = (c & 1) | ((c >> 7) & 2);
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if(opaque || ch)
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ppu_write(p,
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layer,
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x + (flipx ? 7 - h : h),
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y + (flipy ? 7 - v : v),
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blending[ch][color]);
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}
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}
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}
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void
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ppu_debug(Ppu *p, Uint8 *stack, Uint8 wptr, Uint8 rptr, Uint8 *memory)
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{
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Uint8 i, x, y, b;
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for(i = 0; i < 0x20; ++i) {
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x = ((i % 8) * 3 + 1) * 8, y = (i / 8 + 1) * 8, b = stack[i];
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/* working stack */
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ppu_blit(p, &p->fg, x, y, font[(b >> 4) & 0xf], 1 + (wptr == i) * 0x7, 0, 0, 0);
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ppu_blit(p, &p->fg, x + 8, y, font[b & 0xf], 1 + (wptr == i) * 0x7, 0, 0, 0);
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y = 0x28 + (i / 8 + 1) * 8;
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b = memory[i];
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/* return stack */
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ppu_blit(p, &p->fg, x, y, font[(b >> 4) & 0xf], 3, 0, 0, 0);
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ppu_blit(p, &p->fg, x + 8, y, font[b & 0xf], 3, 0, 0, 0);
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}
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/* return pointer */
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ppu_blit(p, &p->fg, 0x8, y + 0x10, font[(rptr >> 4) & 0xf], 0x2, 0, 0, 0);
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ppu_blit(p, &p->fg, 0x10, y + 0x10, font[rptr & 0xf], 0x2, 0, 0, 0);
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/* guides */
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for(x = 0; x < 0x10; ++x) {
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ppu_write(p, &p->fg, x, p->height / 2, 2);
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ppu_write(p, &p->fg, p->width - x, p->height / 2, 2);
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ppu_write(p, &p->fg, p->width / 2, p->height - x, 2);
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ppu_write(p, &p->fg, p->width / 2, x, 2);
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ppu_write(p, &p->fg, p->width / 2 - 0x10 / 2 + x, p->height / 2, 2);
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ppu_write(p, &p->fg, p->width / 2, p->height / 2 - 0x10 / 2 + x, 2);
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}
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}
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