Read .map file from mos-nes-mmc3 target and summarize RAM/ROM usage

section_summary.py

import re
import sys

TOTAL_SYSTEM_RAM = 0x800 # 2kb built into the NES
TOTAL_WORK_RAM = 0x2000  # 8kb of PRG RAM thanks to the mapper TODO: banking?

TOTAL_PRG_BANKS = 64
PRG_BANK_SIZE = 0x2000   # 8KiB banks

TOTAL_CHR_BANKS = 256
CHR_BANK_SIZE = 0x0400   # 1KiB banks

ZP_SIZE = 0x100
ZP_RESERVED = 0x20       # Compiler uses 32 bytes (customizable) for registers.
SRAM_SIZE = TOTAL_SYSTEM_RAM - ZP_SIZE

SWSTACK_SIZE = 0x100
WRAM_SIZE = TOTAL_WORK_RAM - SWSTACK_SIZE

PRG_BANKS_RESERVED = 2   # Fixed banks from 0xC000-0xFFFF
AVAILABLE_PRG_BANKS = TOTAL_PRG_BANKS - PRG_BANKS_RESERVED

with open(sys.argv[1], "r") as file:
    zp_left = ZP_SIZE - ZP_RESERVED
    sram_left = SRAM_SIZE
    wram_left = WRAM_SIZE
    fixed_prg_left = PRG_BANK_SIZE * PRG_BANKS_RESERVED
    prg_rom_left = [PRG_BANK_SIZE] * AVAILABLE_PRG_BANKS
    used_prg_banks = set()
    chr_banks_left = TOTAL_CHR_BANKS

    for line in file:
        try:
            vma, lma, size, _, section = line.split()
            vma = int(vma, 16)
            lma = int(lma, 16)
            size = int(size, 16)
            section = re.match(r"^(\.[\w.]+)$", section).groups()[0]
        except:
            continue

        # TODO: use memory regions and the values of vma/lma instead of
        # hard-coded string names/patterns
        if section.startswith(".debug"):
            continue

        if section in [".comment", ".symtab", ".shstrtab", ".strtab"]:
            continue

        if section.startswith(".zp"):
            zp_left -= size
            if (vma != lma):
                # Data-like segment; initializer value is in ROM, but program
                # accesses it through RAM
                fixed_prg_left -= size
        elif section in [".bss", ".noinit"]:
            wram_left -= size
        elif section == ".data":
            wram_left -= size
            fixed_prg_left -= size
        elif section in [".text", ".rodata", ".dpcm", ".reset", ".vectors"]:
            fixed_prg_left -= size
        elif segment == ".ram":
            sram_left -= size
        elif section == ".chr_rom":
            assert(size % CHR_BANK_SIZE == 0)
            chr_banks_left -= size // CHR_BANK_SIZE
        elif match := re.match(r".prg_rom_(\d*)", section):
            index = int(match.groups()[0])
            prg_rom_left[index] -= size
            used_prg_banks.add(index)
        else:
            raise ValueError(f"Unknown section: {section}")

    remaining_prg_banks = AVAILABLE_PRG_BANKS - len(used_prg_banks)

print(f"""
Remaining RAM bytes:
     ZP: {zp_left:5d}
   SRAM: {sram_left:5d}
   WRAM: {wram_left:5d}

Remaining PRG ROM bytes:
  FIXED: {fixed_prg_left:5d}""")

if used_prg_banks:
    for i in range(0, max(used_prg_banks) + 1):
        if i in used_prg_banks:
            print(f"""\
    PRG{i:02d}: {prg_rom_left[i]:5d}""")
        else:
            print(f"""\
    PRG{i:02d}: {PRG_BANK_SIZE:5d} (Unused)""")

print(f"""
Available ROM banks:
    PRG: {remaining_prg_banks:5d} ({round(remaining_prg_banks * PRG_BANK_SIZE / 1024)} KiB)
    CHR: {chr_banks_left:5d} ({chr_banks_left} KiB)""")