This is a custom emulator that I wrote for the 16 bit intel 8080 architecture, that is also a debugger, and a disassembler. I mainly wrote this, so I could learn how to make these things.
To compile the code, you can just use make. All of the source code is under src:
$ git clone git@github.com:guyinatuxedo/Nightfall-Emulator.git
$ cd Nightfall-Emulator/src/
$ make
gcc Nightfall.c emulate.c debugCmds.c disass.c flagSet.c math.c stack.c utills.c debugUtils.c codeExec.c mov.c -o Nightfall
When I was first working on this, I made a python disassembler, which you can find under disassembler.
I documented how to make an emulator, debugger, and disassembler under how-to-make.
To use the emulator, it takes a single argument which is the binary file you wish to emulate:
$ ./Nightfall block2/testcase007
Nightfall 8080 Emualtor / Debugger / Disassembler
ndb>
you can disassemble a loaded file with the e command:
ndb> e
0x0: mvi b, 0x4
0x2: mvi c, 0x10
0x4: mvi d, 0x88
0x6: mvi e, 0xba
0x8: mvi h, 0x5
0xa: mvi l, 0x6
0xc: mvi m, 0x27
0xe: mvi a, 0x4
0x10: add b
0x11: add c
0x12: add d
0x13: add e
0x14: add h
0x15: add l
0x16: add m
0x17: add a
0x18: end 0x66
to emulate the binary, use r:
ndb> r
to set a breakpoint for 0x6, use b <adr>:
ndb> b 0x6
ndb> r
Breakpoint hit at 0x6
to list all breakpoints, use z:
ndb> z
Breakpoint 0x0 at 6 (active: 1)
Breakpoint 0x1 at a (active: 1)
Breakpoint 0x2 at e (active: 1)
to deactivate a breakpoint, use d <breakpoint>:
ndb> d 0x2
ndb> z
Breakpoint 0x0 at 6 (active: 1)
Breakpoint 0x1 at a (active: 1)
Breakpoint 0x2 at e (active: 0)
to activate a breakpoint, use a <breakpoint>:
ndb> a 0x2
ndb> z
Breakpoint 0x0 at 6 (active: 1)
Breakpoint 0x1 at a (active: 1)
Breakpoint 0x2 at e (active: 1)
to continue execution after you have hit a breakpoint, use c:
ndb> r
Breakpoint hit at 0x6
ndb> c
Breakpoint hit at 0xa
ndb> c
Breakpoint hit at 0xe
ndb> c
to list the contents of all of the registers and flags, use i:
ndb> r
Breakpoint hit at 0x6
ndb> i
8 bit registers
register a: 0x0
register b: 0x4
register c: 0x10
register d: 0x88
register e: 0x0
register h: 0x0
register l: 0x0
16 bit registers
register bc: 0x410
register de: 0x8800
register hl: 0x0
register af: 0x2
Flags
7: Sign flag: 0
6: Zero flag: 0
5: zero1 flag (value shouldn't change): 0
4: Auxillary flag: 0
3: zero2 flag (value shouldn't change): 0
2: Parity flag: 0
1: one flag (value shouldn't change): 1
0: Carry flag: 0
Stack registers (16 bit)
register pc: 0x6
register sp: 0x4000
Interrupt bit: 0x1
to jump to a different place of the code manually, use j (you will need to continue using c afterwards):
ndb> z
Breakpoint 0x0 at 6 (active: 1)
Breakpoint 0x1 at a (active: 1)
Breakpoint 0x2 at e (active: 1)
ndb> r
Breakpoint hit at 0x6
ndb> j 0xe
ndb> c
Breakpoint hit at 0xe
to list the memory mapping use m(just tells you where the stack, code, and total memroy regions are):
ndb> r
Breakpoint hit at 0x6
ndb> m
Total Memory Region: 0x0 - 0xffff
Code Memory Region: 0x0 - 0x19
Stack Memory Region: 0x4000 - 0x4000
to print the contents of a register, use p <register>:
ndb> r
Breakpoint hit at 0x6
ndb> p d
register d: 0x88
ndb> p de
register de: 0x8800
to quit the debugger, use q:
ndb> r
Breakpoint hit at 0x6
ndb> q
to step an instruction, use s (just execute the next instruction):
ndb> r
Breakpoint hit at 0x6
ndb> p e
register e: 0x0
ndb> s
Stepped to 0x8
ndb> p e
register e: 0xba
to toggle disassemble use t (disassembles all instructions that are ran):
ndb> t
ndb> r
0x0: mvi b, 0x4
0x2: mvi c, 0x10
0x4: mvi d, 0x88
Breakpoint hit at 0x6
ndb> c
0x6: mvi e, 0xba
0x8: mvi h, 0x5
Breakpoint hit at 0xa
ndb> c
0xa: mvi l, 0x6
0xc: mvi m, 0x27
Breakpoint hit at 0xe
ndb> c
0xe: mvi a, 0x4
0x10: add b
0x11: add c
0x12: add d
0x13: add e
0x14: add h
0x15: add l
0x16: add m
0x17: add a
0x18: end 0x66
to dump the contents of the memory to the file memory.dat, use u (dumps all memory between 0x0 - 0xffff):
ndb> r
Breakpoint hit at 0x6
ndb> u
ndb> q
$ ls | grep memory.dat
memory.dat
to examine a memory address, use x <addr> (this example uses a different testcase):
./Nightfall block1/testcase004
Nightfall 8080 Emualtor / Debugger / Disassembler
ndb> e
0x0: mvi h, 0x20
0x2: mvi l, 0x40
0x4: mov c, l
0x5: mov a, l
0x6: mov d, h
0x7: mov b, a
0x8: mvi c, 0x0
0xa: mov c, b
0xb: mov e, b
0xc: mov e, d
0xd: mov m, b
0xe: mov m, c
0xf: mov m, d
0x10: mov m, e
0x11: mov m, h
0x12: mov m, l
0x13: mov m, a
0x14: end 0x66
ndb> b 0xd
ndb> r
Breakpoint hit at 0xd
ndb> p b
register b: 0x40
ndb> p hl
register hl: 0x2040
ndb> x 0x2040
0x2040: 0x0
ndb> s
Stepped to 0xe
ndb> x 0x2040
0x2040: 0x40
to set a register, or memory address to a specific 8 bit value, use either y <register> <value> or y <addr> <value>. This uses testcase004 (same as x) :
ndb> r
Breakpoint hit at 0xd
ndb> p hl
register hl: 0x2040
ndb> x 0x2040
0x2040: 0x0
ndb> p b
register b: 0x40
ndb> y b 0x66
ndb> p b
register b: 0x66
ndb> s
Stepped to 0xe
ndb> x 0x2040
0x2040: 0x66
or to set an address equal to a value:
ndb> x 0x2040
0x2040: 0x40
ndb> y 0x2040 0x66
ndb> x 0x2040
0x2040: 0x66
to print the help menu:
ndb> h
Help Menu
a <breakpoint id> - Activate a previously deacticated breakpoint
b <code address> - Set a breakpoint at the address
c - Continue execution from a breakpoint
d <breakpoint id> - Deactivate a breakpoint
e - Disassemble all code in binary
h - Print help menu
i - Display values of all registers and flags
j <next adr> - Set the next address to be executed (essentially a jump, but need to continue)
m - Print the addresses for memory regions
p <register> - Prints contents of register
q - Quit the emulator/debugger
r - Run the emulator from the start
s - Step to the next instruction
t - Toggle running disassembly, which disassembles instructions as they are ran
u - Dump the contents of memory to the file memory.dat
x <amnt> <adr> - Print amnt 8 bit segments starting at adr (if single argument given, amnt is 1)
y <target <value> - Set target register or address to value
z - Show all breakpoints, and if they are activated
Here are some sources which have really helped me with writing this:
https://pmd85.borik.net/instrset/instuction-set.html
http://www.emulator101.com/reference/8080-by-opcode.html
http://pastraiser.com/cpu/i8080/i8080_opcodes.html
http://altairclone.com/downloads/manuals/8080%20Programmers%20Manual.pdf
^8080 manual
http://www.emulator101.com/
I implemented the opcode 0xdd to include end functionallity with the emulator. It takes a single argument indicating what you want to do, and at them moment I have only one option which is 0x66 which ends the program. So if you see 0xdd66 or end 0x66 that ends the program.