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apps,litenes,ppu: re-organize pattern table to fetch XHLidx friendly

This commit is contained in:
Zihao Yu 2019-05-01 13:46:02 +08:00
parent 14422979c5
commit 5da7efea86
1 changed files with 16 additions and 9 deletions
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25
apps/litenes/src/ppu.c
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@ -15,6 +15,7 @@ static byte ppu_addr_latch;
static bool ppu_sprite_hit_occured = false;
static uint16_t ppu_bg_XHLidx_for_sprite0_check[264][264 / 8];
static uint16_t ppu_bg_XHLidx[264][(264 + W) / 8];
static uint16_t pattern2XHLidx[16][256];
static const word ppu_base_nametable_addresses[4] = { 0x2000, 0x2400, 0x2800, 0x2C00 };
@ -185,6 +186,18 @@ static void table_init() {
ppu_ram_map[x] = ppu_get_real_ram_address(x);
}
log("ppu_ram_map[0x3F00]=0x%x\n", ppu_ram_map[0x3F00]);
// pattern table is read only!
// re-organize the pattern table to fetch XHLidx friendly
uint32_t addr;
for (addr = 0; addr < 0x2000; addr ++) {
uint32_t y_in_tile = addr & 0x7;
uint32_t bitplane = (addr >> 3) & 1;
uint32_t lr_idx = addr >> 12;
uint32_t tile_idx = (addr >> 4) & 0xff;
if (bitplane) pattern2XHLidx[(lr_idx << 3) | y_in_tile][tile_idx] |= (PPU_RAM[addr] << 8);
else pattern2XHLidx[(lr_idx << 3) | y_in_tile][tile_idx] = PPU_RAM[addr];
}
}
static uint32_t color_cache[4][4];
@ -267,7 +280,6 @@ extern bool do_update;
static inline void ppu_draw_background_scanline(bool mirror) {
int tile_y = ppu.scanline >> 3;
int taddr = base_nametable_address | (tile_y << 5);
int pattern_table_base = background_pattern_table_address | (ppu.scanline & 0x7);
int tile_x_max = 32;
int tile_x = ppu_shows_background_in_leftmost_8px() ? 0 : 1;
@ -279,25 +291,20 @@ static inline void ppu_draw_background_scanline(bool mirror) {
}
else if (ppu.PPUSCROLL_X > 0) {
tile_x += skip_tiles;
taddr += skip_tiles;
}
uint16_t *p_bg_sprite0 = &ppu_bg_XHLidx_for_sprite0_check[ppu.scanline][0];
uint16_t *p_bg = &ppu_bg_XHLidx[ppu.scanline][mirror ? W / 8 : 0];
uint16_t *p_XHLidx = &pattern2XHLidx[(background_pattern_table_address >> 9) | (ppu.scanline & 7)][0];
for (; tile_x < tile_x_max; tile_x ++) {
int tile_index = ppu_ram_read_fast(taddr);
uint32_t tile_address = pattern_table_base | (tile_index << 4);
uint32_t l = ppu_ram_read_fast(tile_address);
uint32_t XHLidx = (ppu_ram_read_fast(tile_address + 8) << 8) | l;
int tile_index = ppu_ram_read_fast(taddr + tile_x);
uint32_t XHLidx = p_XHLidx[tile_index];
// most of the tiles of bg are transparent, which are unnecessary to process
p_bg[tile_x] = XHLidx;
if (XHLidx != 0) {
p_bg_sprite0[tile_x] = XHLidx;
}
taddr ++;
}
}