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Disassembler for 6502 processors
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Nathan Rosenquist 8b01d8b204 Use fread() return value to count bytes 
This commit changes the behavior of dcc6502, so that it consults the
return value of fread(), and then increments the value of byte_count
by the number returned by fread(), rather than implicitly incrementing
it every time.

Previously, a warning occurred during compilation, because the return value
of fread() was ignored. Instead, the number of bytes in the input file were
counted implicitly by incrementing a byte_count variable after every fread()
call.

Additionally, I created a two-byte test input file consisting of the
bytes #$a9ff, which corresponds to LDA #$FF. When dcc6502 tried to
disassemble this input file, it reported that the file had a size of three
bytes. It reported the first two opcodes correctly, but then incorrectly
displayed a BRK as the third opcode.

After this change, the input file now has a reported size of two bytes,
without the phantom BRK opcode at the end.
 		2018-09-01 20:44:41 -04:00
.gitignore Updated .gitignore 2014-07-24 23:22:12 -04:00
LICENSE Initial commit 2014-07-23 13:44:07 -04:00
Makefile Added Makefile and cleaned-up indent 2014-07-23 14:57:21 -04:00
README.md Updated README.md 2014-07-23 14:16:22 -04:00
dcc6502.c Use fread() return value to count bytes 2018-09-01 20:44:41 -04:00

README.md

dcc6502

Disassembler for 6502 processors.

Features

  • Simple command-line interface
  • Single file, ANSI C source
  • Annotation for addresses of Nintendo Entertainment System (NES) system registers
  • Cycle-counting output
  • Machine code display inline with the disassembly

History tidbit

The original 1.0 version of dcc6502 was written overnight on Christmas eve 1998. At the time, I (Tennessee Carmel-Veilleux) was a 16-year-old NES hacker learning 6502 assembly. Of course, as many teenagers are, I was a bit arrogant and really thought my code was pretty hot back then :) Fast-forward 15 years and I'm a grown-up engineer who is quite a bit more humble about his code. Looking back, I think the tool did the job, but obviously, 15 years of experience later, I would have made it quite a bit cleaner. The disassembler has floated online on miscalleanous NES development sites since 1998. I decided to put it on github starting at version 1.4 and I will be cleaning-up the code over until version 2.0.

This disassembler has made the rounds and has been used for a lot of different purposes by many different people over the years. Hopefully it will continue to be useful going forward.