kobzol / davis

Assembly debugger written in Angular 2.

x86 assembly debugger

This tool allows writing, running and debugging x86 assembly in the browser.
It visualizes the program state (cpu and memory), supports breakpoints and
enables line-by-line stepping.

You can try it online here.

Features

• x86 assembly editor
  • Intel/NASM syntax with syntax-highlighting
  • breakpoints
  • current execution line highlight
• CPU emulation
  • run, stop, pause, continue, step execution
  • register and status flags visualization
  • tick rate setting
• Memory visualization
  • variable byte size (1/2/4)
  • ASCII visualization
• Output console

TODO

• Stack visualizer
• Register dereference visualiser
• Proper arithmetic using 16-bit? calculations
• More instructions
• Enable comments on empty lines

##Installation Run npm install.

Usage

Opens the site in browser.

npm start

###Tests

npm test

###Build Builds the application into dist folder.

npm run build

davis's Issues

Fix dereference access

section .data
string_origin:
db 'ahojx', 0
string_result:
db ' ', 0
string_len:
dd 0x5

section .text
MOV ECX, [string_len]
load:
MOV EDX, string_origin
MOV BL, BYTE [EDX + ECX * 1 - 1]
SUB BL, BYTE 32
MOV EDX, string_result
MOV [EDX + ECX * 1 - 1], EBX

DEC ECX
CMP ECX, 0
JE end
JMP load

end:
HLT

MOV [EDX + ECX * 1 - 1], EBX is not working correctly

Usability

Could you make the UI closer to the one that inspired you https://schweigi.github.io/assembler-simulator/

When a mem location or register changes then show a different colour.
Use horizontal spae more effectively - eg 16 wide mem and not 8.

Take alook back at .. https://schweigi.github.io/assembler-simulator/

Thanks

Enable .data labels in dereference

.data labels cannot be used in [dereference].

Enable empty lines with comments in parser

Fix CMP instruction

I think SBB emulation is broken.

By the spec it's defined as DEST ← (DEST – (SRC + CF));

But I think it's implemented as DEST ← (DEST – SRC + CF);

Reproducible with this snippet.

    MOV EAX, 10
    MOV EBX, -1 ; 
    ADD EBX, 1 ; CF = 1
    SBB EAX, 0 ; EAX = (EAX - (0 + CF)) = EAX - 1 = 9
    ; EAX should be 9, it is 11

Recognize partial register access

BL → BYTE EBX etc.

Logical Opcodes not implemented

Logical Operators(e.g Xor and And) not implemented

Fix .data labels

Labels in .data section (except the first label) are treated as .text labels.

Move to a newer version of Angular

Add LOOP instructions to parser