Instruction fixes

Author: nathsou

codegen/hash.c

@@ -7,7 +7,7 @@
 #define HASH_OFFSET_BASIS 2166136261
 #define HASH_PRIME 16777619
 #define RECORDING_FRAME_COUNT 7987
-#define EXPECTED_CUMULATIVE_HASH 788985578
+#define EXPECTED_CUMULATIVE_HASH 1633679932
 
 static NESInputRecording recording;
 static uint32_t frame_counter = 0;

codegen/lib/cpu.c

@@ -123,43 +123,63 @@ void update_nz(uint8_t value) {
     neg_flag = (value & 0b010000000) != 0;
 }
 
-uint8_t zero_page(uint8_t addr) {
-    return read_byte(addr);
+inline uint8_t zero_page(uint8_t addr) {
+    return read_byte((uint16_t)addr);
 }
 
-uint8_t zero_page_x(uint8_t addr) {
-    return read_byte((addr + x) & 0xff); // TODO: check if wrapping is necessary
+inline uint8_t zero_page_x_addr(uint8_t addr) {
+    return addr + x;
 }
 
-uint8_t zero_page_y(uint8_t addr) {
-    return read_byte(addr + y);
+inline uint8_t zero_page_x(uint8_t addr) {
+    return read_byte((uint16_t)zero_page_x_addr(addr));
 }
 
-uint8_t absolute(uint16_t addr) {
+inline uint8_t zero_page_y_addr(uint8_t addr) {
+    return addr + y;
+}
+
+inline uint8_t zero_page_y(uint8_t addr) {
+    return read_byte((uint16_t)zero_page_y_addr(addr));
+}
+
+inline uint8_t absolute(uint16_t addr) {
     return read_byte(addr);
 }
 
-uint8_t absolute_x(uint16_t addr) {
-    return read_byte(addr + x);
+inline uint16_t absolute_x_addr(uint16_t addr) {
+    return addr + x;
+}
+
+inline uint8_t absolute_x(uint16_t addr) {
+    return read_byte(absolute_x_addr(addr));
 }
 
-uint8_t absolute_y(uint16_t addr) {
+inline uint8_t absolute_y(uint16_t addr) {
     return read_byte(addr + y);
 }
 
-uint16_t indirect_x_addr(uint8_t addr) {
-    return read_word(addr + x);
+inline uint16_t indirect_x_addr(uint8_t addr) {
+    uint8_t addr1 = addr + x;
+    uint8_t addr2 = addr1 + 1; // zero page wrap around
+    uint16_t low_byte = (uint16_t)read_byte(addr1);
+    uint16_t high_byte = (uint16_t)(((uint16_t)read_byte(addr2)) << 8);
+    return high_byte | low_byte;
+    return read_word(addr1);
 }
 
-uint16_t indirect_y_addr(uint8_t addr) {
-    return read_word(addr) + y;
+inline uint16_t indirect_y_addr(uint8_t addr) {
+    uint8_t addr2 = addr + 1; // zero page wrap around
+    uint16_t low_byte = (uint16_t)read_byte(addr);
+    uint16_t high_byte = (uint16_t)(((uint16_t)read_byte(addr2)) << 8);
+    return (high_byte | low_byte) + (uint16_t)y;
 }
 
-uint8_t indirect_x_val(uint8_t addr) {
+inline uint8_t indirect_x_val(uint8_t addr) {
     return read_byte(indirect_x_addr(addr));
 }
 
-uint8_t indirect_y_val(uint8_t addr) {
+inline uint8_t indirect_y_val(uint8_t addr) {
     return read_byte(indirect_y_addr(addr));
 }
 

codegen/lib/cpu.h

@@ -40,6 +40,7 @@ uint8_t zero_page_x(uint8_t addr);
 uint8_t zero_page_y(uint8_t addr);
 
 uint8_t absolute(uint16_t addr);
+uint16_t absolute_x_addr(uint16_t addr);
 uint8_t absolute_x(uint16_t addr);
 uint8_t absolute_y(uint16_t addr);
 

codegen/lib/instructions.c

@@ -84,8 +84,8 @@ void ldy_absx(uint16_t addr) {
 // ADC - Add with Carry
 
 void adc_imm(uint8_t value) {
-    uint16_t sum = a + value + (carry_flag ? 1 : 0);
-    carry_flag = sum > 0xff;
+    uint16_t sum = (uint16_t)a + (uint16_t)value + (uint16_t)carry_flag;
+    carry_flag = sum & 0x100;
     a = (uint8_t)sum;
     update_nz(a);
 }
@@ -510,28 +510,32 @@ void rol_abs(uint16_t addr) {
 
 // ROR - Rotate Right
 
-void ror_acc(void) {
+void _ror(uint16_t addr) {
+    uint8_t val = read_byte(addr);
     bool old_carry = carry_flag;
-    carry_flag = a & 1;
-    a >>= 1;
+    carry_flag = val & 1;
+    val >>= 1;
 
     if (old_carry) {
-        a |= 0x80;
+        val |= 0x80;
     }
 
-    update_nz(a);
+    dynamic_ram_write(addr, val);
+    update_nz(val);
 }
 
-void ror_absx(uint16_t addr) {
-    uint8_t val = absolute_x(addr);
+inline void ror_acc(void) {
     bool old_carry = carry_flag;
-    carry_flag = val & 1;
-    val >>= 1;
+    carry_flag = a & 1;
+    a >>= 1;
 
     if (old_carry) {
-        val |= 0x80;
+        a |= 0x80;
     }
 
-    dynamic_ram_write(addr, val);
-    update_nz(val);
+    update_nz(a);
+}
+
+inline void ror_absx(uint16_t addr) {
+    _ror(absolute_x_addr(addr));
 }