arch/m68k-amiga/boot/romcheck.c

   1 /*
   2     Copyright © 1995-2017, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: m68k-amiga ROM checksum generator
   6     Lang: english
   7  */
   8
   9 #include <stdint.h>
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <unistd.h>
  13 #include <fcntl.h>
  14 #include <errno.h>
  15
  16 #include <sys/mman.h>
  17
  18 static int amiga_checksum(uint8_t *mem, int size, uint32_t chkoff, int update)
  19 {
  20     uint32_t oldcksum = 0, cksum = 0, prevck = 0;
  21     int i;
  22
  23     for (i = 0; i < size; i+=4) {
  24         uint32_t val = (mem[i+0] << 24) +
  25                        (mem[i+1] << 16) +
  26                        (mem[i+2] <<  8) +
  27                        (mem[i+3] <<  0);
  28
  29         /* Clear existing checksum */
  30         if (update && i == chkoff) {
  31                 oldcksum = val;
  32                 val = 0;
  33         }
  34
  35         cksum += val;
  36         if (cksum < prevck)
  37             cksum++;
  38         prevck = cksum;
  39     }
  40
  41     cksum = ~cksum;
  42
  43     if (update && cksum != oldcksum) {
  44         printf("Updating checksum from 0x%08x to 0x%08x\n", oldcksum, cksum);
  45
  46         mem[chkoff + 0] = (cksum >> 24) & 0xff;
  47         mem[chkoff + 1] = (cksum >> 16) & 0xff;
  48         mem[chkoff + 2] = (cksum >>  8) & 0xff;
  49         mem[chkoff + 3] = (cksum >>  0) & 0xff;
  50
  51         return 1;
  52    }
  53
  54    return 0;
  55 }
  56
  57 int main(int argc, char **argv)
  58 {
  59         int err, fd, i, retval = EXIT_FAILURE;
  60         void *rom;
  61         uint8_t *p;
  62         uint32_t size = 0;
  63         off_t origlen, len;
  64
  65         fd = open(argv[1], O_RDWR | O_CREAT, 0666);
  66         if (fd < 0) {
  67             perror(argv[1]);
  68             return retval;
  69         }
  70
  71         origlen = lseek(fd, 0, SEEK_END);
  72
  73         /* Make sure we have a valid ROM ID */
  74         rom = mmap(NULL, origlen, PROT_READ | PROT_WRITE,
  75                 MAP_SHARED, fd, 0);
  76         if (rom == MAP_FAILED)
  77         {
  78             perror(argv[1]);
  79             close(fd);
  80             return retval;
  81         }
  82         p = (uint8_t*)rom;
  83         if (p[0] == 0x11 && (p[1] >= 0x11 || p[1] <= 0x14))
  84         {
  85             if (p[1] == 0x11)
  86             {
  87                 size = 256 * 1024;
  88                 if (origlen > size)
  89                 {
  90                     printf("Warning: ROM ID is for a 256K ROM, but the image is larger -> promoting to 512KB ROM.\n");
  91                     p[1] = 0x14;
  92                 }
  93             }
  94             if (p[1] == 0x14)
  95                 size = 512 * 1024;
  96         }
  97         if (size == 0)
  98             printf("Error: Invalid ROM ID (%02x%02x).\n", p[0], p[1]);
  99         munmap(rom, origlen);
 100         if (size == 0)
 101         {
 102             close(fd);
 103             return retval;
 104         }
 105
 106         len = origlen;
 107
 108         if (len > size)
 109         {
 110             printf("Error: ROM Size > %uKB", size/1024);
 111             if ((len - size) >= 1024)
 112                 printf(" (+%luKB).\n", (len - size)/1024);
 113             else
 114                 printf(" (+%luB).\n", (len - size));
 115             return retval;
 116         }
 117
 118         /* Pad with 0xff */
 119         for (; len < size; len++) {
 120             unsigned char padb;
 121
 122 #if (0)
 123             /* Earlier kickstarts used 0x00 as the pad byte.. */
 124             padb = 0x0;
 125 #else
 126             padb = 0xff;
 127 #endif
 128             write(fd, &padb, 1);
 129         }
 130
 131         rom = mmap(NULL, len, PROT_READ | PROT_WRITE,
 132                         MAP_SHARED, fd, 0);
 133
 134         if (rom != MAP_FAILED)
 135         {
 136             p = (uint8_t*)rom + len - 20;
 137             if ((origlen <= (size - 24)) ||
 138                 ((p[0] == (len >> 24) & 0xFF) &&
 139                  (p[1] == (len >> 16) & 0xFF) &&
 140                  (p[2] == (len >>  8) & 0xFF) &&
 141                  (p[3] == (len >> 0) & 0xFF)))
 142             {
 143                 /* Make sure the rom size is set*/
 144                 p[0] = len >> 24;
 145                 p[1] = len >> 16;
 146                 p[2] = len >>  8;
 147                 p[3] = len >>  0;
 148
 149                 /* Add the interrupt vector offsets,
 150                  * needed by 68000 and 68010 */
 151                 p = (uint8_t*)rom + len - 16;
 152                 for (i = 0; i < 8; i++) {
 153                         p[i * 2 + 1] = i + 0x18;
 154                         p[i * 2 + 0] = 0;
 155                 }
 156
 157                 err = amiga_checksum(rom, len, len - 24, 0);
 158                 err = amiga_checksum(rom, len, len - 24, 1);
 159
 160                 retval = EXIT_SUCCESS;
 161             }
 162             else
 163             {
 164                 printf("Error: Rom Data Size exceeds available space (%lu bytes remaining).\n", size - origlen);
 165             }
 166
 167             munmap(rom, len);
 168         }
 169         else
 170             perror(argv[1]);
 171
 172         close(fd);
 173
 174         return retval;
 175 }
 176
 177