/* lkgb.c */

/*
 * P. Felber
 */

#ifdef GAMEBOY

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include "aslink.h"

/* Value used to fill the unused portions of the image */
/* FFh puts less stress on a EPROM/Flash */
#define FILLVALUE	0xFF

#define CARTSIZE ((unsigned long)nb_rom_banks*16UL*1024UL)
#define NBSEG 8UL
#define SEGSIZE (CARTSIZE/NBSEG)

#define ROMSIZE 0x8000UL
#define BANKSTART 0x4000UL
#define BANKSIZE 0x4000UL

unsigned char *cart[NBSEG];

int nb_rom_banks;
int nb_ram_banks;
int current_rom_bank;
int mbc_type;
char cart_name[16] = "";

patch* patches = NULL;

VOID gb(int in)
{
  static int first = 1;
  unsigned long pos, chk;
  int i;
  patch *p;

  if(first) {
    for(i = 0; i < NBSEG; i++) {
      if((cart[i] = malloc(SEGSIZE)) == NULL) {
	fprintf(stderr, "ERROR: can't allocate %dth segment of memory (%d bytes)\n", i, (int)SEGSIZE);
	exit(-1);
      }
      memset(cart[i], FILLVALUE, SEGSIZE);
    }
    first = 0;
  }
  if(in) {
    if(rtcnt > 2) {
      if(hilo == 0)
	pos = rtval[0] | (rtval[1]<<8);
      else
	pos = rtval[1] | (rtval[0]<<8);

      /* Perform some validity checks */
      if(pos >= ROMSIZE) {
	fprintf(stderr, "ERROR: address overflow (addr %lx >= %lx)\n", pos, ROMSIZE);
	exit(-1);
      }
      if(current_rom_bank >= nb_rom_banks) {
	fprintf(stderr, "ERROR: bank overflow (addr %x > %x)\n", current_rom_bank, nb_rom_banks);
	exit(-1);
      }
      if(current_rom_bank > 0 && pos < BANKSTART) {
	fprintf(stderr, "ERROR: address underflow (addr %lx < %lx)\n", pos, BANKSTART);
	exit(-1);
      }
      if(nb_rom_banks == 2 && current_rom_bank > 0) {
	fprintf(stderr, "ERROR: only 1 32kB segment with 2 bank\n");
	exit(-1);
      }
      if(current_rom_bank > 1)
	pos += (current_rom_bank-1)*BANKSIZE;
      for(i = 2; i < rtcnt; i++) {
	if(rtflg[i]) {
	  if(pos < CARTSIZE) {
	    if(cart[pos/SEGSIZE][pos%SEGSIZE] != FILLVALUE)
	      fprintf(stderr, "WARNING: possibly wrote twice at addr %lx (%02X->%02X)\n", pos, rtval[i], cart[pos/SEGSIZE][pos%SEGSIZE]);
	    cart[pos/SEGSIZE][pos%SEGSIZE] = rtval[i];
	  } else {
	    fprintf(stderr, "ERROR: cartridge size overflow (addr %lx >= %lx)\n", pos, CARTSIZE);
	    exit(-1);
	  }
	  pos++;
	}
      }
    }
  } else {
    /* EOF */
    if(cart_name[0] == 0 && linkp->f_idp != NULL) {
      for(i = strlen(linkp->f_idp);
	  i > 0 && (isalnum(linkp->f_idp[i-1]) || linkp->f_idp[i-1] == '.');
	  i--)
	;
      for(pos = 0; pos < 16 && linkp->f_idp[i] != '.'; pos++, i++)
	cart_name[pos] = toupper(linkp->f_idp[i]);
      if(pos < 16)
	cart_name[pos] = 0;
    }
    for(pos = 0x0134, i = 0;
	pos < 0x0144 && cart_name[i];
	pos++, i++)
      cart[pos/SEGSIZE][pos%SEGSIZE] = cart_name[i];
    for(; pos < 0x0144; pos++)
      cart[pos/SEGSIZE][pos%SEGSIZE] = 0;
    cart[0x147/SEGSIZE][0x147%SEGSIZE] = mbc_type;
    switch(nb_rom_banks) {
    case 2:
      cart[0x148/SEGSIZE][0x148%SEGSIZE] = 0;
      break;
    case 4:
      cart[0x148/SEGSIZE][0x148%SEGSIZE] = 1;
      break;
    case 8:
      cart[0x148/SEGSIZE][0x148%SEGSIZE] = 2;
      break;
    case 16:
      cart[0x148/SEGSIZE][0x148%SEGSIZE] = 3;
      break;
    case 32:
      cart[0x148/SEGSIZE][0x148%SEGSIZE] = 4;
      break;
    case 64:
      cart[0x148/SEGSIZE][0x148%SEGSIZE] = 5;
      break;
    case 128:
      cart[0x148/SEGSIZE][0x148%SEGSIZE] = 6;
      break;
    case 256:
      cart[0x148/SEGSIZE][0x148%SEGSIZE] = 7;
      break;
    case 512:
      cart[0x148/SEGSIZE][0x148%SEGSIZE] = 8;
      break;
    default:
      fprintf(stderr, "WARNING: unsupported number of ROM banks (%d)\n", nb_rom_banks);
      cart[0x148/SEGSIZE][0x148%SEGSIZE] = 0;
      break;
    }
    switch(nb_ram_banks) {
    case 0:
      cart[0x149/SEGSIZE][0x149%SEGSIZE] = 0;
      break;
    case 1:
      cart[0x149/SEGSIZE][0x149%SEGSIZE] = 2;
      break;
    case 4:
      cart[0x149/SEGSIZE][0x149%SEGSIZE] = 3;
      break;
    case 16:
      cart[0x149/SEGSIZE][0x149%SEGSIZE] = 4;
      break;
    default:
      fprintf(stderr, "WARNING: unsupported number of RAM banks (%d)\n", nb_ram_banks);
      cart[0x149/SEGSIZE][0x149%SEGSIZE] = 0;
      break;
    }

    /* Patch before calculating the checksum */
    if(patches)
      for(p = patches; p; p = p->next)
	cart[p->addr/SEGSIZE][p->addr%SEGSIZE] = p->value;

    /* Update complement checksum */
    chk = 0;
    for(pos = 0x0134; pos < 0x014D; pos++)
      chk += cart[pos/SEGSIZE][pos%SEGSIZE];
    cart[0x014D/SEGSIZE][0x014D%SEGSIZE] = 0xE7 - (chk&0xFF);
    /* Update checksum */
    chk = 0;
    cart[0x014E/SEGSIZE][0x014E%SEGSIZE] = 0;
    cart[0x014F/SEGSIZE][0x014F%SEGSIZE] = 0;
    for(i = 0; i < NBSEG; i++)
      for(pos = 0; pos < SEGSIZE; pos++)
	chk += cart[i][pos];
    cart[0x014E/SEGSIZE][0x014E%SEGSIZE] = (chk>>8)&0xFF;
    cart[0x014F/SEGSIZE][0x014F%SEGSIZE] = chk&0xFF;

    for(i = 0; i < NBSEG; i++)
      fwrite(cart[i], 1, SEGSIZE, ofp);
  }
}

#endif /* GAMEBOY */