From 7c4d6cea3f8e6be2b11cadba47a20b0a40c837a8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rados=C5=82aw=20Kujawa?= <radoslaw.kujawa@c0ff33.net>
Date: Sat, 31 Mar 2018 12:38:45 +0200
Subject: [PATCH] Fix indirect indexed with Y addressing.

Also fix test case for this. Problem wasn't detected, because test case
was broken too.
---
 src/instruction.c     | 10 ++++------
 test/test_emulation.c |  8 ++++----
 2 files changed, 8 insertions(+), 10 deletions(-)

diff --git a/src/instruction.c b/src/instruction.c
index 350a730..6845f54 100644
--- a/src/instruction.c
+++ b/src/instruction.c
@@ -302,11 +302,10 @@ instruction_data_write_1(rk65c02emu_t *e, instrdef_t *id, instruction_t *i, uint
 		iaddr |= (bus_read_1(e->bus, i->op1 + e->regs.X + 1) << 8);
 		bus_write_1(e->bus, iaddr, val);
 		break;
-	case IZPY:
-		/* XXX */
+	case IZPY: /* Zero Page Indirect Indexed with Y */
 		iaddr = bus_read_1(e->bus, i->op1);
 		iaddr |= (bus_read_1(e->bus, i->op1 + 1) << 8);
-		bus_write_1(e->bus, iaddr, val + e->regs.Y);
+		bus_write_1(e->bus, iaddr + e->regs.Y, val);
 		break;
 	case ABSOLUTEX:
 		bus_write_1(e->bus, (i->op1 + (i->op2 << 8)) + e->regs.X, val);
@@ -369,11 +368,10 @@ instruction_data_read_1(rk65c02emu_t *e, instrdef_t *id, instruction_t *i)
 		iaddr |= (bus_read_1(e->bus, i->op1 + e->regs.X + 1) << 8);
 		rv = bus_read_1(e->bus, iaddr);
 		break;
-	case IZPY:
-		/* XXX: what about page wraps / roll over */
+	case IZPY: /* Zero Page Indirect Indexed with Y */
 		iaddr = bus_read_1(e->bus, i->op1);
 		iaddr |= (bus_read_1(e->bus, i->op1 + 1) << 8);
-		rv = bus_read_1(e->bus, iaddr) + e->regs.Y;
+		rv = bus_read_1(e->bus, iaddr + e->regs.Y);
 		break;
 	case ABSOLUTE:
 		rv = bus_read_1(e->bus, i->op1 + (i->op2 << 8));
diff --git a/test/test_emulation.c b/test/test_emulation.c
index 34d1fa5..65d97c8 100644
--- a/test/test_emulation.c
+++ b/test/test_emulation.c
@@ -122,7 +122,7 @@ ATF_TC_BODY(emul_cmp, tc)
 	e.regs.Y = 0x01;
 	bus_write_1(&b, 0x22, 0x0);
 	bus_write_1(&b, 0x23, 0x20);
-	bus_write_1(&b, 0x2000, 0xF);
+	bus_write_1(&b, 0x2001, 0x10);
 	rk65c02_dump_regs(e.regs);
 	ATF_REQUIRE(rom_start(&e, "test_emulation_cmp_izpy.rom", tc));
 	rk65c02_dump_regs(e.regs);
@@ -662,11 +662,11 @@ ATF_TC_BODY(emul_sta, tc)
 	ATF_REQUIRE(rom_start(&e, "test_emulation_sta_izpx.rom", tc));
 	ATF_CHECK(bus_read_1(&b, 0x2010) == 0xAA);
 	/* STA indirect zero page Y */
-	e.regs.A = 0x54;
+	e.regs.A = 0x55;
 	e.regs.X = 0;
 	e.regs.Y = 0x1;
 	ATF_REQUIRE(rom_start(&e, "test_emulation_sta_izpy.rom", tc));
-	ATF_CHECK(bus_read_1(&b, 0x2010) == 0x55);
+	ATF_CHECK(bus_read_1(&b, 0x2011) == 0x55);
 
 	bus_finish(&b);
 }
@@ -729,7 +729,7 @@ ATF_TC_BODY(emul_ora, tc)
 	e.regs.A = 0xAA;
 	e.regs.X = 0;
 	e.regs.Y = 0x1;
-	bus_write_1(&b, 0x2A04, 0x54);
+	bus_write_1(&b, 0x2A05, 0x55);
 	bus_write_1(&b, 0x14, 0x04);
 	bus_write_1(&b, 0x15, 0x2A);
 	ATF_REQUIRE(rom_start(&e, "test_emulation_ora_izpy.rom", tc));