sim65 is used as part of the toolchain to test 6502 or 65C02 code.
The binary to test should be compiled with --target sim6502 or --target sim65c02.
The simulator is called as follows:
Usage: sim65 [options] file [arguments]
Short options:
-h Help (this text)
-c Print amount of executed CPU cycles
-v Increase verbosity
-V Print the simulator version number
-x <num> Exit simulator after <num> cycles
Long options:
--help Help (this text)
--cycles Print amount of executed CPU cycles
--verbose Increase verbosity
--version Print the simulator version number
sim65 will exit with the error code of the simulated program, which is limited to an 8-bit result 0-255.
An error in sim65, like bad arguments or an internal problem will exit with 1.
A timeout from -x will exit with 2.
Here is a description of all the command line options:
-h, --helpPrint the short option summary shown above.
-c, --cyclesPrint the number of executed CPU cycles when the program terminates.
The cycles for the final "jmp exit" are not included in this
count.
-v, --verboseIncrease the simulator verbosity.
-V, --versionPrint the version number of the utility. When submitting a bug report, please include the operating system you're using, and the compiler version.
-x numExit simulator after num cycles.
The simulator will read one binary file per invocation and can log the program loading and paravirtualization calls to stderr.
Example output for the command
sim65 --verbose --verbose samples/gunzip65
Loaded 'samples/gunzip65' at $0200-$151F
PVWrite ($0001, $13C9, $000F)
GZIP file name:PVWrite ($0001, $151F, $0001)
PVRead ($0000, $FFD7, $0001)
PVOpen ("", $0001)
PVRead ($0003, $1520, $6590)
PVClose ($0003)
PVWrite ($0001, $13D9, $000F)
Not GZIP formatPVWrite ($0001, $151F, $0001)
PVExit ($01)
For a C test linked with --target sim6502 and the sim6502.lib library,
command line arguments to sim65 will be passed to main,
and the return value from main will become sim65's exit code.
The stdlib.h exit function may also be used to terminate with an exit code.
Exit codes are limited to an unsigned 8 bit value. (E.g. returning -1 will give an exit code of 255.)
The standard C library high level file input and output is functional.
A sim65 application can be written like a command line application,
providing command line arguments to main and using the stdio.h interfaces
to interact with the console or access files.
Internally, file input and output is provided at a lower level by a set of built-in paravirtualization functions (see below).
Example:
#include <stdio.h>
int main()
{
printf("Hello!\n");
return 5;
}
// Build and run:
// cl65 -t sim6502 -o example.prg example.c
// sim65 example.prg
// Build and run, separate steps:
// cc65 -t sim6502 -o example.s example.c
// ca65 -t sim6502 -o example.o example.s
// ld65 -t sim6502 -o example.prg example.o sim6502.lib
// sim65 example.prg
Though a C test may also link with assembly code, a pure assembly test can also be created.
Link with --target sim6502 or --target sim65c02 and the corresponding library,
define and export _main as an entry point,
and the sim65 library provides two ways to return an 8-bit exit code:
_main with the exit code in A.
jmp exit with the code in A. (.import exit from the sim65 library.)
Example:
.export _main
_main:
lda #5
rts
; Build and run:
; cl65 -t sim6502 -o example.prg example.s
; sim65 example.prg
; Build and run, separate steps:
; ca65 -t sim6502 -o example.o example.s
; ld65 -t sim6502 -o example.prg example.o sim6502.lib
; sim65 example.prg
Internally, the binary program file has a 12 byte header provided by the library:
$73, $69, $6D, $36, $35 or 'sim65'
2
0 = 6502, 1 = 65C02
sp used by the paravirtualization functions
$0200)
$0200)
Other internal details:
$FFFC will be
pre-loaded with the given reset address.
exit address is $FFF9.
Jumping to this address will terminate execution with the A register value as an exit code.
exit, a JSR to one of these addresses will return immediately after performing a special function.
These use cc65 calling conventions, and are intended for use with the sim65 target C library.
IRQ and NMI events will not be generated, though BRK
can be used if the IRQ vector at $FFFE is manually prepared by the test code.
sim6502 or sim65c02 targets provide a default configuration,
but if customization is needed sim6502.cfg or sim65c02.cfg might be used as a template.
sim65 (and all cc65 binutils) are (C) Copyright 1998-2000 Ullrich von Bassewitz. For usage of the binaries and/or sources the following conditions do apply:
This software is provided 'as-is', without any expressed or implied warranty. In no event will the authors be held liable for any damages arising from the use of this software.
Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions: