From 4165c1cefc7d440752cc0454d89ed2e4b7c09ff4 Mon Sep 17 00:00:00 2001
From: Peter Evans <pevans@activecampaign.com>
Date: Sat, 27 Jan 2018 13:04:19 -0600
Subject: [PATCH] Make idx, idy clearer

I'm still not confident this is how it _should_ work, but I have found
conflicting accounts online for the behavior of these two modes. The
current code is what allows the Apple II to bootstrap as it should.
---
 src/mos6502.addr.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/src/mos6502.addr.c b/src/mos6502.addr.c
index 01d61c7..c007725 100644
--- a/src/mos6502.addr.c
+++ b/src/mos6502.addr.c
@@ -168,12 +168,14 @@ DEFINE_ADDR(ind)
  */
 DEFINE_ADDR(idx)
 {
-    ADDR_LO(cpu);
-    EFF_ADDR(addr + cpu->X);
+    vm_8bit addr;
 
-    return mos6502_get(
-        cpu, 
-        mos6502_get(cpu, eff_addr));
+    addr = mos6502_get(cpu, cpu->PC + 1);
+    addr = mos6502_get(cpu, addr + cpu->X);
+
+    EFF_ADDR(addr);
+
+    return mos6502_get(cpu, eff_addr);
 }
 
 /*
@@ -184,8 +186,12 @@ DEFINE_ADDR(idx)
  */
 DEFINE_ADDR(idy)
 {
-    ADDR_LO(cpu);
-    EFF_ADDR(mos6502_get(cpu, addr) + cpu->Y);
+    vm_8bit addr;
+
+    addr = mos6502_get(cpu, cpu->PC + 1);
+    addr = mos6502_get(cpu, addr);
+
+    EFF_ADDR(addr + cpu->Y);
 
     return mos6502_get(cpu, eff_addr);
 }