Dave Van Wagner
6502 emulator for Commodore 64 ROMs, serial terminal edition for MBED. Recommend terminal echo on, line edit on, caps lock, 115200bps, implicit carriage return on newline, currently non-buffered so don't paste lots of stuff
More details at:
[https://github.com/davervw] [https://techwithdave.davevw.com/2020/03/simple-emu-c64.html]
Diff: emu6502.cpp
- Revision:
- 8:519febdce8db
- Parent:
- 7:f49fa56672d8
--- a/emu6502.cpp Mon Apr 13 05:13:26 2020 +0000
+++ b/emu6502.cpp Wed Apr 15 05:15:07 2020 +0000
@@ -58,7 +58,7 @@
extern void ResetRun(bool (*ExecutePatch)(void))
{
- ushort addr = (ushort)((GetMemory(0xFFFC) | (GetMemory(0xFFFD) << 8))); // RESET vector
+ ushort addr = (ushort)((GetMemory(0xFFFC) | (GetMemory(0xFFFD) << 8))); // JMP(RESET)
Execute(addr, ExecutePatch);
}
@@ -96,17 +96,6 @@
return (byte)(value >> 8);
}
-static void BRK(byte *p_bytes)
-{
- ++PC;
- Push(HI(PC));
- Push(LO(PC));
- PHP();
- B = true;
- PC = (ushort)(GetMemory(0xFFFE) + (GetMemory(0xFFFF) << 8));
- *p_bytes = 0;
-}
-
static byte Subtract(byte reg, byte value, bool *p_overflow)
{
bool old_reg_neg = (reg & 0x80) != 0;
@@ -498,6 +487,17 @@
*p_addr = (ushort)((hi << 8) | lo);
}
+static void BRK(byte *p_bytes)
+{
+ ++PC;
+ Push(HI(PC));
+ Push(LO(PC));
+ PHP();
+ B = true;
+ PC = (ushort)(GetMemory(0xFFFE) + (GetMemory(0xFFFF) << 8)); // JMP(IRQ)
+ *p_bytes = 0;
+}
+
static void JMP(ushort *p_addr, byte *p_bytes)
{
*p_bytes = 0; // caller should not advance address