everything working, 2285 fps

1 files changed, 106 insertions, 74 deletions

diff --git a/ppu.c b/ppu.c
index d67cff3..db78b91 100644
--- a/ppu.c
+++ b/ppu.c
@@ -124,8 +124,8 @@ static inline uint8_t ppu_read(struct nes_state *state, uint32_t offset) {
 	return result;
 }
 
-__attribute__((always_inline, hot))
-static inline void ppu_evaluate_sprites(struct nes_state *state) {
+__attribute__((hot))
+static void ppu_evaluate_sprites(struct nes_state *state) {
 	struct ppu_state *ppu = &state->ppu;
 	uint8_t sprite_height = (ppu->reg_ctrl & 0x20) ? 16 : 8;
 	uint8_t n = 0;
@@ -143,7 +143,7 @@ static inline void ppu_evaluate_sprites(struct nes_state *state) {
 				dst[2] = src[2];
 				dst[3] = src[3];
 				ppu->sprite_indexes[n] = i;
-				ppu->sprite_zero_hit_possible |= (i == 0) ? 1 : 0;
+				ppu->sprite_zero_hit_possible |= (i == 0);
 
 				dst += 4;
 				n++;
@@ -158,30 +158,32 @@ static inline void ppu_evaluate_sprites(struct nes_state *state) {
 	ppu->sprite_count = n;
 }
 
-__attribute__((always_inline, hot))
-static inline void ppu_fetch_sprite_patterns(struct nes_state *state) {
+__attribute__((hot))
+static void ppu_fetch_sprite_patterns(struct nes_state *state) {
 	struct ppu_state *ppu = &state->ppu;
+	uint32_t addr;
+	uint32_t bank;
+
+	uint8_t *s = ppu->secondary_oam;
+	uint8_t height = (ppu->reg_ctrl & 0x20) ? 16 : 8;
+
 	for(uint8_t i = 0; i < ppu->sprite_count; i++) {
-		uint8_t *s = ppu->secondary_oam + i * 4;
 		uint8_t y = s[0], tile = s[1], attr = s[2], x = s[3];
 		uint8_t row = ppu->scanline - y;
-		uint8_t height = (ppu->reg_ctrl & 0x20) ? 16 : 8;
 
 		row = (attr & 0x80) ? height - 1 - row : row;
 
-		uint32_t addr;
 		if(height == 16) {
-			uint32_t bank = (tile & 1) ? 0x1000 : 0x0000;
+			bank = (tile & 1) << 12;
 			tile &= 0xfe;
 			if(row >= 8) {
 				tile++;
 				row -= 8;
 			}
-			addr = bank + tile * 16 + row;
 		} else {
-			uint32_t bank = (ppu->reg_ctrl & 0x08) ? 0x1000 : 0x0000;
-			addr = bank + tile * 16 + row;
+			bank = (ppu->reg_ctrl & 0x08) << 9;
 		}
+		addr = bank + tile * 16 + row;
 
 		uint8_t lsb = state->mapper.chr_read(state, addr);
 		uint8_t msb = state->mapper.chr_read(state, addr + 8);
@@ -194,73 +196,107 @@ static inline void ppu_fetch_sprite_patterns(struct nes_state *state) {
 		ppu->sprite_shift_lo[i] = lsb;
 		ppu->sprite_shift_hi[i] = msb;
 		ppu->sprite_positions[i] = x;
-		ppu->sprite_priorities[i] = (attr >> 5) & 1;
+		ppu->sprite_priorities[i] = attr & 0x20;
+		s += 4;
 	}
 }
 
-__attribute__((always_inline, hot))
-static inline void ppu_render_pixel(struct nes_state *state) {
+__attribute__((hot))
+static void ppu_render_pixel(struct nes_state *state) {
+	struct ppu_state *ppu = &state->ppu;
+
+	uint32_t x = ppu->dot - 1;
+	uint32_t y = ppu->scanline;
+
+	// Fine X shift mask
+	// static const uint16_t fine_shift[8] = { 0x8000, 0x4000, 0x2000, 0x1000, 0x0800, 0x0400, 0x0200, 0x0100 };
+	uint16_t bit = 0x8000 >> ppu->fine_x;//fine_shift[ppu->fine_x];
+
 	uint8_t bg_pixel = 0;
 	uint8_t bg_palette = 0;
 	uint8_t sp_pixel = 0;
 	uint8_t sp_palette = 0;
 	uint8_t sp_prio = 0;
 	uint8_t sp_zero = 0;
-	uint8_t final_color = 0;
 
-	struct ppu_state *ppu = &state->ppu;
+#if 1		// TODO(peter): Decide what I prefer, masking away unlikely path, or LIKELY hint to the compiler
+	uint8_t bg_mask = (ppu->reg_mask & 0x08) ? 0xff : 0x00;
+	uint8_t sp_mask = (ppu->reg_mask & 0x10) ? 0xff : 0x00;
 
-	uint32_t x = ppu->dot - 1;
-	uint32_t y = ppu->scanline;
+	// Background
+	uint8_t p0 = !!(ppu->bg_shift_pattern_low & bit);
+	uint8_t p1 = !!(ppu->bg_shift_pattern_high & bit);
+	uint8_t a0 = !!(ppu->bg_shift_attrib_low & bit);
+	uint8_t a1 = !!(ppu->bg_shift_attrib_high & bit);
+
+	bg_pixel   = ((p1 << 1) | p0) & bg_mask;
+	bg_palette = ((a1 << 1) | a0) & bg_mask;
+
+	// Sprite
+	for(uint8_t i = 0; i < ppu->sprite_count; i++) {
+		if(ppu->sprite_positions[i]) continue;
 
-	uint32_t bit = 0x8000 >> ppu->fine_x;
+		uint8_t lo = ppu->sprite_shift_lo[i];
+		uint8_t hi = ppu->sprite_shift_hi[i];
+		sp_pixel = (((hi & 0x80) >> 6) | ((lo & 0x80) >> 7)) & sp_mask;
 
-	if(ppu->reg_mask & 0x08) {
-		uint8_t p0 = (ppu->bg_shift_pattern_low & bit) ? 1 : 0;
-		uint8_t p1 = (ppu->bg_shift_pattern_high & bit) ? 1 : 0;
+		if(!sp_pixel) continue;
+
+		sp_palette = ppu->secondary_oam[i * 4 + 2] & 3;
+		sp_prio    = ppu->sprite_priorities[i];
+		sp_zero    = (ppu->sprite_indexes[i] == 0);
+		break;
+	}
+#else
+	// Background fetch
+	if(LIKELY(ppu->reg_mask & 0x08)) {
+		uint8_t p0 = !!(ppu->bg_shift_pattern_low & bit);
+		uint8_t p1 = !!(ppu->bg_shift_pattern_high & bit);
 		bg_pixel = (p1 << 1) | p0;
 
-		uint8_t a0 = (ppu->bg_shift_attrib_low & bit) ? 1 : 0;
-		uint8_t a1 = (ppu->bg_shift_attrib_high & bit) ? 1 : 0;
+		uint8_t a0 = !!(ppu->bg_shift_attrib_low & bit);
+		uint8_t a1 = !!(ppu->bg_shift_attrib_high & bit);
 		bg_palette = (a1 << 1) | a0;
 	}
 
-	if(ppu->reg_mask & 0x10) {
+	// Sprite fetch
+	if(LIKELY(ppu->reg_mask & 0x10)) {
 		for(uint8_t i = 0; i < ppu->sprite_count; i++) {
-			if(ppu->sprite_positions[i] == 0) {
-				uint8_t p0 = (ppu->sprite_shift_lo[i] & 0x80) ? 1 : 0;
-				uint8_t p1 = (ppu->sprite_shift_hi[i] & 0x80) ? 1 : 0;
-				sp_pixel = (p1 << 1) | p0;
-
-				if(sp_pixel) {
-					sp_palette = ppu->secondary_oam[i * 4 + 2] & 3;
-					sp_prio = ppu->sprite_priorities[i];
-					sp_zero = (ppu->sprite_indexes[i] == 0);
-					break;
-				}
-			}
-		}
-	}
+			if(ppu->sprite_positions[i]) continue;
 
-	if(bg_pixel == 0 && sp_pixel == 0) {
-		final_color = ppu->palette[0];
-	} else if(bg_pixel == 0 && sp_pixel != 0) {
-		final_color = ppu->palette[0x10 | (sp_palette << 2) | sp_pixel];
-	} else if(bg_pixel != 0 && sp_pixel == 0) {
-		final_color = ppu->palette[(bg_palette << 2) | bg_pixel];
-	} else {
-		if(sp_zero && ppu->sprite_zero_hit_possible && x < 255) {
-			ppu->reg_status |= 0x40;
-		}
-		if(sp_prio == 0) {
-			final_color = ppu->palette[0x10 | (sp_palette << 2) | sp_pixel];
-		} else {
-			final_color = ppu->palette[(bg_palette << 2) | bg_pixel];
+			uint8_t lo = ppu->sprite_shift_lo[i];
+			uint8_t hi = ppu->sprite_shift_hi[i];
+			sp_pixel = ((hi & 0x80) >> 6) | ((lo & 0x80) >> 7);
+
+			if(!sp_pixel) continue;
+
+			sp_palette = ppu->secondary_oam[i * 4 + 2] & 3;
+			sp_prio    = ppu->sprite_priorities[i];
+			sp_zero    = (ppu->sprite_indexes[i] == 0);
+			break;
 		}
 	}
-	ppu->pixels[y * 256 + x] = final_color;
-}
+#endif
+	// Final pixel composition
+	uint8_t palette_index = 0;
+	uint8_t bg_index = (bg_palette << 2) + bg_pixel;
+	uint8_t sp_index = (sp_palette << 2) + sp_pixel;
+	uint8_t selector = (bg_pixel ? 2 : 0) | (sp_pixel ? 1 : 0);
+
+	switch(selector) {
+		case 0: { palette_index = 0;						} break;
+		case 1: { palette_index = 0x10 | sp_index;	} break;
+		case 2: { palette_index = bg_index;				} break;
+		case 3: {
+			if(sp_zero && ppu->sprite_zero_hit_possible && x < 255) {
+				ppu->reg_status |= 0x40;
+			}
+			palette_index = (sp_prio) ? bg_index : 0x10 | sp_index;
+		} break;
+	}
 
+	state->pixels[y * 256 + x] = ppu->palette[palette_index];		// NOTE(peter): Add color_emphasis bits (expand palette to 8x).
+}
 
 __attribute__((hot, flatten))
 static void ppu_tick(struct nes_state *state) {
@@ -272,7 +308,6 @@ static void ppu_tick(struct nes_state *state) {
 
 	for(uint32_t ppu_loops = 0; ppu_loops < 3; ++ppu_loops) {
 
-
 		if(LIKELY(rendering)) {
 
 			if(ppu->even_frame && dot == 0) {
@@ -284,28 +319,25 @@ static void ppu_tick(struct nes_state *state) {
 				ppu_render_pixel(state);
 			}
 
-			if((dot >= 1 && dot <= 256) || (dot >= 321 && dot <= 336)) {
+			if(scanline < 240 || scanline == 261) {
+				if((dot >= 1 && dot <= 256) || (dot >= 321 && dot <= 336)) {
 
-				if(ppu->reg_mask & 0x10) {
-					for(uint32_t i = 0; i < ppu->sprite_count; i++) {
-						if(ppu->sprite_positions[i] > 0) {
-							ppu->sprite_positions[i]--;
-						} else {
-							ppu->sprite_shift_lo[i] <<= 1;
-							ppu->sprite_shift_hi[i] <<= 1;
+					if(ppu->reg_mask & 0x10) {
+						for(uint32_t i = 0; i < ppu->sprite_count; i++) {
+							if(ppu->sprite_positions[i] > 0) {
+								ppu->sprite_positions[i]--;
+							} else {
+								ppu->sprite_shift_lo[i] <<= 1;
+								ppu->sprite_shift_hi[i] <<= 1;
+							}
 						}
 					}
-				}
-
-				ppu->bg_shift_pattern_low <<= 1;
-				ppu->bg_shift_pattern_high <<= 1;
-				ppu->bg_shift_attrib_low <<= 1;
-				ppu->bg_shift_attrib_high <<= 1;
-			}
 
+					ppu->bg_shift_pattern_low <<= 1;
+					ppu->bg_shift_pattern_high <<= 1;
+					ppu->bg_shift_attrib_low <<= 1;
+					ppu->bg_shift_attrib_high <<= 1;
 
-			if(scanline < 240 || scanline == 261) {
-				if((dot >= 1 && dot <= 256) || (dot >= 321 && dot <= 336)) {
 					switch(dot % 8) {
 						case 1: {
 							uint32_t nt_addr = 0x2000 | (ppu->vram_addr & 0x0fff);