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#include <SDL2/SDL.h>
#include <stdbool.h>
#include "ppu/consts.h"
#include "ppu/internals.h"
#include "ppusim/mem.h"
#include "ppusim/work.h"
/* transform xy if tile is flipped */
static uint16_t hh_ppusim_apply_transform(unsigned x, unsigned y, bool fliph, bool flipv) {
unsigned tx = fliph ? HH_PPU_SPRITE_WIDTH - x - 1 : x;
unsigned ty = flipv ? HH_PPU_SPRITE_HEIGHT - y - 1 : y;
return ty * HH_PPU_SPRITE_WIDTH + tx;
}
/* @brief get current bg pixel cidx */
static uint8_t hh_ppusim_bg_pixel(unsigned x, unsigned y) {
hh_ppu_data_t *aux = &g_hh_ppusim_vram[HH_PPU_VRAM_AUX_OFFSET];
unsigned bg_shift_y = HH_RESIZE(aux[0], 7, 0);
unsigned bg_shift_x = HH_RESIZE(aux[0], 15, 8) | HH_RESIZE(aux[1], 0, 0) << 8;
unsigned abs_x = bg_shift_x + x;
unsigned abs_y = bg_shift_y + y;
unsigned grid_x = abs_x / HH_PPU_SPRITE_WIDTH;
unsigned grid_y = abs_y / HH_PPU_SPRITE_HEIGHT;
unsigned loc_x = abs_x - grid_x * HH_PPU_SPRITE_WIDTH;
unsigned loc_y = abs_y - grid_y * HH_PPU_SPRITE_HEIGHT;
unsigned bam_offset = grid_y * HH_PPU_BG_CANVAS_TILES_H + grid_x;
hh_ppu_data_t bam = g_hh_ppusim_vram[HH_PPU_VRAM_BAM_OFFSET + bam_offset];
uint8_t cidx = 0;
uint16_t tile_pixel_idx = hh_ppusim_apply_transform(loc_x, loc_y, HH_RESIZE(bam, 14, 14), HH_RESIZE(bam, 13, 13));
uint16_t tile_idx = HH_RESIZE(bam, 9, 0);
hh_ppu_addr_t ttm_addr = tile_idx * HH_PPU_VRAM_TMM_SPRITE_SIZE + tile_pixel_idx / 5;
uint8_t word_bit_addr = (tile_pixel_idx % 5) * 3;
hh_ppu_data_t tmm = g_hh_ppusim_vram[HH_PPU_VRAM_TMM_OFFSET + ttm_addr];
cidx |= HH_RESIZE(bam, 12, 10) << 3;
cidx |= HH_RESIZE(tmm, word_bit_addr + 2, word_bit_addr) << 0;
return cidx;
}
/* @brief get current fg pixel cidx */
static uint8_t hh_ppusim_fg_pixel(unsigned x, unsigned y) {
x += 16;
y += 16;
uint8_t cidx = 0;
for (unsigned i = 0; i < HH_PPU_FG_SPRITE_COUNT; i++) {
unsigned fam_offset = i * HH_PPU_VRAM_FAM_ENTRY_SIZE;
hh_ppu_data_t *fam = &g_hh_ppusim_vram[HH_PPU_VRAM_FAM_OFFSET + fam_offset];
unsigned sprite_y = HH_RESIZE(fam[0], 15, 13) | HH_RESIZE(fam[1], 4, 0) << 3;
unsigned sprite_x = HH_RESIZE(fam[1], 13, 5);
if (x < sprite_x) continue;
if (x >= sprite_x + HH_PPU_SPRITE_WIDTH) continue;
if (y < sprite_y) continue;
if (y >= sprite_y + HH_PPU_SPRITE_HEIGHT) continue;
unsigned loc_x = x - sprite_x;
unsigned loc_y = y - sprite_y;
uint16_t tile_pixel_idx = hh_ppusim_apply_transform(loc_x, loc_y, HH_RESIZE(fam[1], 15, 15), HH_RESIZE(fam[1], 14, 14));
uint16_t tile_idx = HH_RESIZE(fam[0], 9, 0);
hh_ppu_addr_t ttm_addr = tile_idx * HH_PPU_VRAM_TMM_SPRITE_SIZE + tile_pixel_idx / 5;
uint8_t word_bit_addr = (tile_pixel_idx % 5) * 3;
hh_ppu_data_t tmm = g_hh_ppusim_vram[HH_PPU_VRAM_TMM_OFFSET + ttm_addr];
unsigned cidx_col = HH_RESIZE(tmm, word_bit_addr + 2, word_bit_addr);
if (cidx_col == 0) continue;
unsigned cidx_pal = HH_RESIZE(fam[0], 12, 10);
cidx = (cidx_col << 0) | (cidx_pal << 3);
break;
}
return cidx;
}
void hh_ppusim_pixel(uint8_t *s, unsigned x, unsigned y) {
uint8_t bg_cidx = hh_ppusim_bg_pixel(x, y);
uint8_t fg_cidx = hh_ppusim_fg_pixel(x, y);
uint8_t cidx = (fg_cidx & HH_MASK(3)) == 0 ? bg_cidx : fg_cidx;
hh_ppu_data_t pal_rgb = g_hh_ppusim_vram[HH_PPU_VRAM_PAL_OFFSET + cidx];
hh_ppu_rgb_color_t rgb = {HH_RESIZE(pal_rgb, 11, 8), HH_RESIZE(pal_rgb, 7, 4), HH_RESIZE(pal_rgb, 3, 0)};
s[0] = rgb[0] << 4;
s[1] = rgb[1] << 4;
s[2] = rgb[2] << 4;
}
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