nopsteam / 6502 Goto Github PK

Based on this, we should do exit(1) on any error.

This lines should be changed:
https://github.com/nopsteam/6502/blob/main/src/disassembler.c#L23
https://github.com/nopsteam/6502/blob/main/src/disassembler.c#L28
https://github.com/nopsteam/6502/blob/main/src/disassembler.c#L35
https://github.com/nopsteam/6502/blob/main/src/bus.c#L67
https://github.com/nopsteam/6502/blob/main/src/bus.c#L72
https://github.com/nopsteam/6502/blob/main/src/bus.c#L79

If possible create some tests for this.

We need to add the decimal mode to this emulator.
http://www.6502.org/tutorials/decimal_mode.html

Following the 6502 spec, there is a bug in architecture when indirect addressing mode is used.
Not sure if this thing affects all the indirect addressing like indirect, x and indirect, y but probably yes.
We need to check if the lo(ADDRESS) is 0xFF and, then, consider a full page return, so:

LDX #$02
STX $3000

LDX #$04
STX $3100

LDX #$03
STX $30FF

JMP ($30FF)

the jump will consider the hi(0x3000) + lo(0x30FF) = 0x0203

NB: WE CAN'T USE EASY6502 TO VALIDATE THIS BECAUSE THEY ARE NOT RESPECTING THIS BEHAVIOUR AS WE CAN SEE IN THE PICTURE:

Valgrind is a too that provides a number of debugging and profiling tools that help you make your programs faster and more correct. The most popular of these tools is called Memcheck. It can detect many memory-related errors like memory leaks that are common in C and C++ programs and that can lead to crashes and unpredictable behaviour.

So, would be nice to have it running on every build of this, right?

How to use it
https://www.cprogramming.com/debugging/valgrind.html