cleanup and rewrite of memory_read()

1 files changed, 29 insertions, 122 deletions

diff --git a/ppu_registers.c b/ppu_registers.c
index b426f17..f6bd515 100644
--- a/ppu_registers.c
+++ b/ppu_registers.c
@@ -4,22 +4,26 @@ static inline void ppu_write(struct nes_state *state, uint32_t offset, uint8_t v
 
 	uint32_t reg = offset & 0x7;
 
-	if(reg == 0) {
-		ppu->reg_ctrl = value;
-		ppu->temp_addr = (ppu->temp_addr & 0xf3ff) | ((value & 0x03) << 10);
-		// ppu->open_bus = value;
+	if(LIKELY(reg == 4)) {
+		ppu->oam[ppu->oam_addr++] = value;
+		ppu->open_bus = value;
+		return;
 
 	} else if(reg == 1) {
 		ppu->reg_mask = value;
-		// ppu->open_bus = value;
+		ppu->open_bus = value;
+		return;
+
+	} else if(reg == 0) {
+		ppu->reg_ctrl = value;
+		ppu->temp_addr = (ppu->temp_addr & 0xf3ff) | ((value & 0x03) << 10);
+		ppu->open_bus = value;
+		return;
 
 	} else if(reg == 3) {
 		ppu->oam_addr = value;
-		// ppu->open_bus = value;
-
-	} else if(reg == 4) {
-		ppu->oam[ppu->oam_addr++] = value;
-		// ppu->open_bus = value;
+		ppu->open_bus = value;
+		return;
 
 	} else if(reg == 5) {
 		if(ppu->write_latch == 0) {
@@ -30,7 +34,8 @@ static inline void ppu_write(struct nes_state *state, uint32_t offset, uint8_t v
 			ppu->temp_addr = (ppu->temp_addr & ~0x73e0) | ((value & 0x07) << 12) | ((value & 0xf8) << 2);
 			ppu->write_latch = 0;
 		}
-		// ppu->open_bus = value;
+		ppu->open_bus = value;
+		return;
 
 	} else if(reg == 6) {
 		if(ppu->write_latch == 0) {
@@ -41,11 +46,12 @@ static inline void ppu_write(struct nes_state *state, uint32_t offset, uint8_t v
 			ppu->vram_addr = ppu->temp_addr;
 			ppu->write_latch = 0;
 		}
-		// ppu->open_bus = value;
+		ppu->open_bus = value;
+		return;
 
 	} else if(reg == 7) {
 		uint32_t addr = ppu->vram_addr;
-		if(LIKELY(addr < 0x2000)) {
+		if(addr < 0x2000) {
 			state->mapper.chr_write(state, addr, value);
 
 		} else if(LIKELY(addr < 0x3f00)) {
@@ -59,78 +65,9 @@ static inline void ppu_write(struct nes_state *state, uint32_t offset, uint8_t v
 			ppu->palette[pal_addr] = value;
 		}
 		ppu->vram_addr += (ppu->reg_ctrl & 0x04) ? 32 : 1;
-		// ppu->open_bus = value;
+		ppu->open_bus = value;
+		return;
 	}
-
-	ppu->open_bus = value;
-
-#if 0
-	switch(offset & 7) {
-		case 0: {		// 2000
-			ppu->reg_ctrl = value;
-			ppu->temp_addr = (ppu->temp_addr & 0xf3ff) | ((value & 0x03) << 10);
-			ppu->open_bus = value;
-		} break;
-
-		case 1: {		// 2001
-			ppu->reg_mask = value;
-			ppu->open_bus = value;
-		} break;
-
-		case 3: {		// 2003
-			ppu->oam_addr = value;
-			ppu->open_bus = value;
-		} break;
-
-		case 4: {		// 2004
-			ppu->oam[ppu->oam_addr++] = value;
-			ppu->open_bus = value;
-		} break;
-
-		case 5: {		// 2005
-			if(ppu->write_latch == 0) {
-				ppu->fine_x = value & 0x07;
-				ppu->temp_addr = (ppu->temp_addr & ~0x001f) | (value >> 3);
-				ppu->write_latch = 1;
-			} else {
-				ppu->temp_addr = (ppu->temp_addr & ~0x73e0) | ((value & 0x07) << 12) | ((value & 0xf8) << 2);
-				ppu->write_latch = 0;
-			}
-			ppu->open_bus = value;
-		} break;
-
-		case 6: {		// 2006
-			if(ppu->write_latch == 0) {
-				ppu->temp_addr = (ppu->temp_addr & 0x00ff) | ((value & 0x3f) << 8);
-				ppu->write_latch = 1;
-			} else {
-				ppu->temp_addr = (ppu->temp_addr & 0xff00) | value;
-				ppu->vram_addr = ppu->temp_addr;
-				ppu->write_latch = 0;
-			}
-			ppu->open_bus = value;
-		} break;
-
-		case 7: {		// 2007
-			uint32_t addr = ppu->vram_addr;
-			if(LIKELY(addr < 0x2000)) {
-				state->mapper.chr_write(state, addr, value);
-
-			} else if(LIKELY(addr < 0x3f00)) {
-				state->mapper.ciram_write(state, addr, value);
-
-			} else if(addr < 0x4000) {
-				uint32_t pal_addr = addr & 0x1f;
-				if((pal_addr & 3) == 0) {
-					pal_addr &= ~0x10;
-				}
-				ppu->palette[pal_addr] = value;
-			}
-			ppu->vram_addr += (ppu->reg_ctrl & 0x04) ? 32 : 1;
-			ppu->open_bus = value;
-		} break;
-	}
-#endif
 }
 
 __attribute__((always_inline, hot))
@@ -140,13 +77,17 @@ static inline uint8_t ppu_read(struct nes_state *state, uint32_t offset) {
 
 	uint32_t reg = offset & 0x7;
 
-	if(reg == 2) {
+	if(LIKELY(reg == 2)) {
 		result = ppu->reg_status;
 		ppu->reg_status &= ~0x80;
 		ppu->write_latch = 0;
+		ppu->open_bus = result;
+		return result;
 
-	} else if(reg == 4) {
+	} else if(LIKELY(reg == 4)) {
 		result = ppu->oam[ppu->oam_addr];
+		ppu->open_bus = result;
+		return result;
 
 	} else if(reg == 7) {
 		uint32_t addr = ppu->vram_addr;
@@ -168,45 +109,11 @@ static inline uint8_t ppu_read(struct nes_state *state, uint32_t offset) {
 		}
 
 		ppu->vram_addr += (ppu->reg_ctrl & 0x04) ? 32 : 1;
-	}
-
-#if 0
-	switch(offset & 7) {
-		case 2: {		// 2002
-			result = ppu->reg_status;
-			ppu->reg_status &= ~0x80;
-			ppu->write_latch = 0;
-		} break;
-
-		case 4: {		// 2004
-			result = ppu->oam[ppu->oam_addr];
-		} break;
-
-		case 7: {		// 2007
-			uint32_t addr = ppu->vram_addr;
-
-			if(LIKELY(addr < 0x2000)) {
-				result = ppu->vram_read_buffer;
-				ppu->vram_read_buffer =  state->mapper.chr_read(state, addr);
-
-			} else if(LIKELY(addr < 0x3f00)) {
-				result = ppu->vram_read_buffer;
-				ppu->vram_read_buffer = state->mapper.ciram_read(state, addr);
-
-			} else if(addr < 0x4000) {
-				uint32_t pal_addr = addr & 0x1f;
-				if((pal_addr & 0x13) == 0x10) {
-					pal_addr &= ~0x10;
-				}
-				result = ppu->palette[pal_addr];
-			}
+		ppu->open_bus = result;
+		return result;
 
-			ppu->vram_addr += (ppu->reg_ctrl & 0x04) ? 32 : 1;
-		} break;
 	}
-# endif
 
-	ppu->open_bus = result;
 	return result;
 }