fix ADC bug where V is calculated with new A instead of old A

1 files changed, 2 insertions, 1 deletions

diff --git a/cpu.c b/cpu.c
index 66dbd4c..5d36d37 100644
--- a/cpu.c
+++ b/cpu.c
@@ -218,11 +218,12 @@ adc(uint8_t arg)
         uint16_t sum;   // 16-bit sum makes it easier to determine carry flag
 
         sum = regs.a + arg + regs.status.carry;
-        regs.a = sum & 0xFF;
 
         regs.status.carry = sum > 0xFF;
         /* overflow flag formula: https://stackoverflow.com/a/29224684 */
         regs.status.overflow = (~(regs.a ^ arg) & (regs.a ^ sum) & 0x80) != 0;
+        regs.a = sum & 0xFF;
+
         STATUS_UPDATE_ZERO(regs.a);
         STATUS_UPDATE_NEGATIVE(regs.a);
 }