From 42cb53c0ad6d58cbed7df9e057f0ed86e68c164c Mon Sep 17 00:00:00 2001
From: Takashi Toyoshima <toyoshim@gmail.com>
Date: Mon, 8 Dec 2014 00:36:42 +0900
Subject: [PATCH] Bug fix: after TSX, X got a value >= 0x100

---
 6502.S |  5 +++++
 test.c | 11 +++++++++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/6502.S b/6502.S
index 82978d1..ef0f76d 100644
--- a/6502.S
+++ b/6502.S
@@ -452,6 +452,8 @@
 .endm
 
 .macro _cp reg
+  prn r0
+  prn \reg
   __cl (FLAG_N | FLAG_Z | FLAG_C)
   mov  r1, \reg
   subs r0, r1, r0
@@ -1372,6 +1374,9 @@ opb9:  // LDA - Absolute, Y
 
 opba:  // TSX
   _t   SP, RX
+  mov  r0, RX
+  uxtb r0, r0
+  mov  RX, r0
   _decode
 
 opbc:  // LDY - Absolute, X
diff --git a/test.c b/test.c
index 46be5be..9fd41a2 100644
--- a/test.c
+++ b/test.c
@@ -1,3 +1,4 @@
+#include <assert.h>
 #include <stdio.h>
 #include <stdint.h>
 #include <stdlib.h>
@@ -15,10 +16,16 @@ void prn(int c) {
   __asm__("movs r12, %0":: "r"(fp));
 }
 
-void cpu6502_dump(
-    uint16_t pc, uint8_t a, uint8_t x, uint8_t y, uint8_t sp, uint8_t sr) {
+void cpu6502_dump(uint32_t pc, uint32_t a, uint32_t x, uint32_t y,
+                  uint32_t sp, uint32_t sr) {
   uint8_t fp;
   __asm__("movs %0, r12": "=r"(fp));
+  assert(pc < 0x1000);
+  assert(a < 0x100);
+  assert(x < 0x100);
+  assert(y < 0x100);
+  assert(sr < 0x100);
+  assert(0x100 <= sp && sp < 0x200);
   fprintf(stderr, "*** dump *** PC=$%04x A=$%02x X=$%02x Y=$%02x SP=$%02x "
           "NV-B_DIZC=%d%d-%d_%d%d%d%d\n",
           pc, a, x, y, sp, (sr >> 7) & 1, (sr >> 6) & 1, (sr >> 4) & 1,