emu_nes

commit 99082b55287ecd0378935d31a289c05e1110c7b8
parent 5535e5de70684dd8406e53d6ce928faf9011336c
Author: vin <git@vineetk.net>
Date:   Sun, 30 Jun 2024 07:56:08 -0400

fix JSR, RTS, and RTI

JSR was pushing 1 too high PC and RTS was 1 too low
RTI was only pulling the low byte of PC

Diffstat:
M
cpu.c
 | 
6
+++---

1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/cpu.c b/cpu.c
@@ -472,7 +472,7 @@ jmp(uint16_t arg)
 static void
 jsr(uint16_t arg)
 {
-	uint16_t tmp = regs.pc;
+	uint16_t tmp = regs.pc - 1;
 
 	/*
 	 * first push high-byte of return address then low-byte
@@ -651,13 +651,13 @@ static void
 rti(void)
 {
 	plp();
-	regs.pc = PULL();
+	regs.pc = PULL() | (PULL() << 8);
 }
 
 static void
 rts(void)
 {
-	regs.pc = PULL() | (PULL() << 8);
+	regs.pc = (PULL() | (PULL() << 8)) + 1;
 }
 
 static void