linker_config.cfg

# This is the linker configuration file for this project
# this file exists so we can define the address of
# our memory pages, as ld65's default configuration is suitable
# for C 6502 code, which is not the case.
# so we have copied the original linker configuration, and tweaked it
# to our needs.
# changes:
# ZEROPAGE memory now starts at zero, not two.
# RAM memory now starts at $200, not $6000

# documentation:  https://cc65.github.io/doc/ld65.html#toc5.2
# source:         https://github.com/cc65/cc65/blob/master/cfg/nes.cfg
# inspiration:    https://github.com/bbbradsmith/NES-ca65-example/blob/unix/example.cfg

SYMBOLS {
    __STACKSIZE__: type = weak, value = $0300; # 3 pages stack
}
MEMORY {
    ZP:     file = "", start = $0000, size = $0100, type = rw, define = yes;

    # INES Cartridge Header
    HEADER: file = %O, start = $0000, size = $0010, fill = yes;

    # 2 16K ROM Banks
    # - startup
    # - code
    # - rodata
    # - data (load)
    ROM0:   file = %O, start = $8000, size = $7FFA, fill = yes, define = yes;

    # Hardware Vectors at End of 2nd 8K ROM
    ROMV:   file = %O, start = $FFFA, size = $0006, fill = yes;

    # 1 8k CHR Bank
    ROM2:   file = %O, start = $0000, size = $2000, fill = yes;

    # standard 2k SRAM
    # $0000-$0100 zero page
    # $0100-$0200 cpu stack
    # $0200-$0800 bss
    RAM:   file = "", start = $0200, size = $0600, define = yes;
}
SEGMENTS {
    ZEROPAGE: load = ZP,              type = zp;
    HEADER:   load = HEADER,          type = ro;
    STARTUP:  load = ROM0,            type = ro,  define   = yes;
    LOWCODE:  load = ROM0,            type = ro,  optional = yes;
    ONCE:     load = ROM0,            type = ro,  optional = yes;
    CODE:     load = ROM0,            type = ro,  define   = yes;
    RODATA:   load = ROM0,            type = ro,  define   = yes;
    DATA:     load = ROM0, run = RAM, type = rw,  define   = yes;
    VECTORS:  load = ROMV,            type = rw;
    CHARS:    load = ROM2,            type = rw;
    BSS:      load = RAM,             type = bss, define   = yes, align = $0100;
}
FEATURES {
    CONDES: type    = constructor,
            label   = __CONSTRUCTOR_TABLE__,
            count   = __CONSTRUCTOR_COUNT__,
            segment = ONCE;
    CONDES: type    = destructor,
            label   = __DESTRUCTOR_TABLE__,
            count   = __DESTRUCTOR_COUNT__,
            segment = RODATA;
    CONDES: type    = interruptor,
            label   = __INTERRUPTOR_TABLE__,
            count   = __INTERRUPTOR_COUNT__,
            segment = RODATA,
            import  = __CALLIRQ__;
}