jgilchrist / gbemu Goto Github PK

In the debugger the command parser is looking for strings of mem or memcell in order to view a location or range in the virtual memory:

    if (cmd == "mem") return CommandType::Memory;
    if (cmd == "memcell") return CommandType::MemoryCell;

However, the help menu says to type "memory" or "memory cell":

    printf("memory $start $lines Print a dump of memory from $start to $end\n");
    printf("memorycell $addr     Print the value of the memory at $addr\n");

One or the other should be changed so that they matched. Selfishly, mem and memcell are faster to type.

When calling help within the debugger, we get the following output.

> help
...
= Debug Information
registers            Print a dump of the CPU registers
flags                Print a dump of the CPU flags
....

But the command to print a dump of the registers seems to be just regs.

Hi! Great emulator, I got a custom Gameboy instance working very quickly in my environment. However, I think I am struggling with state restore/save data. I'm saving the get_cartridge_ram() to disk and pass it as save_data in the ctor, but the game I'm trying out is always starting from the beginning. I've tried saving both during the run-loop and afterwards, and data seem to be written (there is binary data in the file). Am I misunderstanding something, or is it maybe the ROM I'm using that is to blame?

delete me

Hi @jgilchrist , I also want to make a Gameboy emulator on C/C++ and I have no idea how to approach the problem. I know I must read Gameboy manual and understand how it works but what do I do after that? I see that you have solved this problem, so will you please explain me how to get started with coding something for this project? Thanks in advance!

PS: I am going to code in Visual Studio 2017, on Windows 10.

| Attempting to read from cartridge RAM
| Attempting to read from cartridge RAM
| Attempting to read from cartridge RAM
| Attempting to read from cartridge RAM
| Attempting to read from cartridge RAM
| Attempting to read from cartridge RAM
| Attempting to read from cartridge RAM
| Attempting to read from cartridge RAM
| Attempting to read from cartridge RAM
| Attempting to read from cartridge RAM
| Attempting to read from cartridge RAM
| Attempting to read from cartridge RAM
| Attempting to read from cartridge RAM
| Attempting to read from cartridge RAM
| Attempting to read from cartridge RAM
| Attempting to read from cartridge RAM
| Attempting to read from cartridge RAM
| Attempting to read from cartridge RAM
| Attempting to read from cartridge RAM
| Boot rom was disabled
| Wrote to sound on/off address 0xff26 - 0x0
| Wrote to sound on/off address 0xff26 - 0x80
| Wrote to selection of sound output terminal address 0xff25 - 0xff
| Wrote to channel control address 0xff24 - 0x77
cpu_instrs

| Attempting to write to cartridge ROM: 2000 - 0x1
01| Wrote to sound on/off address 0xff26 - 0x0
| Wrote to sound on/off address 0xff26 - 0x80
| Wrote to selection of sound output terminal address 0xff25 - 0xff
| Wrote to channel control address 0xff24 - 0x77
:ok | Attempting to write to cartridge ROM: 2000 - 0x1
02| Wrote to sound on/off address 0xff26 - 0x0
| Wrote to sound on/off address 0xff26 - 0x80
| Wrote to selection of sound output terminal address 0xff25 - 0xff
| Wrote to channel control address 0xff24 - 0x77
| Wrote to unknown address 0xff05 - 0x0
:04 | Attempting to write to cartridge ROM: 2000 - 0x1
03| Wrote to sound on/off address 0xff26 - 0x0
| Wrote to sound on/off address 0xff26 - 0x80
| Wrote to selection of sound output terminal address 0xff25 - 0xff
| Wrote to channel control address 0xff24 - 0x77
| Attempted to read from 'Prepare Speed Switch' register
| Attempted to write to 'Prepare Speed Switch' register
| Fatal error @ [opcode_stop:822]
| Stopped

Is it possible to change the clock speed of the emulator? I'd like to make it runs at X2 speed.

I do also wonder why AND touches the F register.

| 0xC321: LD A,C (0x79)
> regs
AF: 0100
BC: 1301
DE: 1300
HL: C304
SP: DFFD
PC: C322
> step
| 0xC322: AND n (0xe6)
> regs
AF: 00A0
BC: 1301
DE: 1300
HL: C304
SP: DFFD
PC: C324

Any documentation I found only talks about A

fuwangqin@fuwangqin-pc:~/code/emulator$ make
-- Found SFML 2.3.2 in /usr/include
-- Configuring done
-- Generating done
-- Build files have been written to: /home/fuwangqin/code/emulator/build
make[1]: Entering directory '/home/fuwangqin/code/emulator/build'
make[2]: Entering directory '/home/fuwangqin/code/emulator/build'
make[3]: Entering directory '/home/fuwangqin/code/emulator/build'
Scanning dependencies of target emulator
make[3]: Leaving directory '/home/fuwangqin/code/emulator/build'
make[3]: Entering directory '/home/fuwangqin/code/emulator/build'
[ 4%] Building CXX object CMakeFiles/emulator.dir/src/address.cc.o
c++: error: unrecognized command line option ‘-Weverything’
CMakeFiles/emulator.dir/build.make:62: recipe for target 'CMakeFiles/emulator.dir/src/address.cc.o' failed
make[3]: *** [CMakeFiles/emulator.dir/src/address.cc.o] Error 1
make[3]: Leaving directory '/home/fuwangqin/code/emulator/build'
CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/emulator.dir/all' failed
make[2]: *** [CMakeFiles/emulator.dir/all] Error 2
make[2]: Leaving directory '/home/fuwangqin/code/emulator/build'
Makefile:83: recipe for target 'all' failed
make[1]: *** [all] Error 2
make[1]: Leaving directory '/home/fuwangqin/code/emulator/build'
Makefile:16: recipe for target 'compile' failed
make: *** [compile] Error 2
fuwangqin@fuwangqin-pc:~/code/emulator$

When i tried running make command, I am getting the following error.

CMake Error at CMakeLists.txt:25 (find_package):
By not providing "FindSDL2.cmake" in CMAKE_MODULE_PATH this project has
asked CMake to find a package configuration file provided by "SDL2", but
CMake did not find one.

Could not find a package configuration file provided by "SDL2" with any of
the following names:

SDL2Config.cmake
sdl2-config.cmake

Add the installation prefix of "SDL2" to CMAKE_PREFIX_PATH or set
"SDL2_DIR" to a directory containing one of the above files. If "SDL2"
provides a separate development package or SDK, be sure it has been
installed.

I was digging into the cpu_instr rom since the 01 special push af test case does not work on my emulator (very early development). After inspecting the test case code and debugging for hours, I am thinking that the test case should never work at all.

Then I saw that your emulator is able to get the test to pass so I used your debugger (thank you for that) to figure out why.

As far as I understand, if a PUSH is followed by a POP directly (no other interactions with the SP register), the POP should write the value, which was previously pushed, to the given register.

> step
| 0xC31D: PUSH BC (0xc5)
> regs
AF: 0000
BC: 1301
DE: 1200
HL: C304
SP: DFFB
PC: C31E
> step
| 0xC31E: POP AF (0xf1)
> regs
AF: 1300
BC: 1301
DE: 1200
HL: C304
SP: DFFD
PC: C31F

Why is AF 0x1300 and not 0x1301?

Hi :-)
i was able to build the emulator following the instructions of the readme file. Just a question, the audio is available at the moment or it has to be add?
I ask you that because at the moment i have no audio output and I don't know if I am missing some dependencies or I need to put some specific option on the cli when I run the emulator. I tested it with super mario land
Thanks,