summaryrefslogtreecommitdiffstats
path: root/rbutil/mkamsboot/mkamsboot.c
blob: 580fde3ebed0ce598ce8fabc559747698126daec (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * mkamsboot.c - a tool for merging bootloader code into an Sansa V2
 *               (AMS) firmware file
 *
 * Copyright (C) 2008 Dave Chapman
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/

/*

Insert a Rockbox bootloader into a Sansa AMS original firmware file.

Layout of a Sansa AMS original firmware file:

 ----------------------  0x0
|        HEADER        |
|----------------------| 0x400
|    FIRMWARE BLOCK    | (contains the OF version on some fuzev2 firmwares
|----------------------| 0x600
|    FIRMWARE BLOCK    |
|----------------------| 0x400 + firmware block size
|    LIBRARIES/DATA    |
 ----------------------  END

We replace the main firmware block while preserving the potential OF version
(bytes 0x600..0x400+firmware_size) as follows:


 ----------------------  0x0
|                      |
|    Dual-boot code    |
|                      |
|----------------------|
|     EMPTY SPACE      |
|----------------------|
|                      |
| compressed RB image  |
|                      |
|----------------------|
|                      |
| compressed OF image  |
|                      |
|----------------------|
| UCL unpack function  |
 ----------------------

This entire block fits into the space previously occupied by the main
firmware block - the space saved by compressing the OF image is used
to store the compressed version of the Rockbox bootloader.

On version 1 firmwares, the OF image is typically about 120KB, which allows
us to store a Rockbox bootloader with an uncompressed size of about 60KB-70KB.
Version 2 firmwares are bigger and are stored in SDRAM (instead of IRAM).
In both cases, the RAM we are using is mapped at offset 0x0.

mkamsboot then corrects the checksums and writes a new legal firmware
file which can be installed on the device.

When the Sansa device boots, this firmware block is loaded to RAM at
address 0x0 and executed.

Firstly, the dual-boot code will copy the UCL unpack function to the
end of RAM.

Then, depending on the detection of the dual-boot keypress, either the
OF image or the Rockbox image is copied to the end of RAM (just before
the ucl unpack function) and uncompressed to the start of RAM.

Finally, the ucl unpack function branches to address 0x0, passing
execution to the uncompressed firmware.


*/

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>

#include <ucl/ucl.h>

#include "mkamsboot.h"

#include "md5.h"

/* Header for ARM code binaries */
#include "dualboot.h"

/* Win32 compatibility */
#ifndef O_BINARY
#define O_BINARY 0
#endif

/* fw_revision: version 2 is used in Clipv2, Clip+ and Fuzev2 firmwares */
/* hw_revision: 4 for m200, 2 for e200/c200, 1 or 2 for fuze/clip, 1 for clip+ */
const struct ams_models ams_identity[] = {
    [MODEL_C200V2]  = { 2, 1, "c200",  dualboot_c200v2,   sizeof(dualboot_c200v2),   "c2v2", 44 },
    [MODEL_CLIPPLUS]= { 1, 2, "Clip+", dualboot_clipplus, sizeof(dualboot_clipplus), "cli+", 66 },
    [MODEL_CLIPV2]  = { 2, 2, "Clip",  dualboot_clipv2,   sizeof(dualboot_clipv2),   "clv2", 60 },
    [MODEL_CLIP]    = { 1, 1, "Clip",  dualboot_clip,     sizeof(dualboot_clip),     "clip", 40 },
    [MODEL_E200V2]  = { 2, 1, "e200",  dualboot_e200v2,   sizeof(dualboot_e200v2),   "e2v2", 41 },
    [MODEL_FUZEV2]  = { 2, 2, "Fuze",  dualboot_fuzev2,   sizeof(dualboot_fuzev2),   "fuz2", 68 },
    [MODEL_FUZE]    = { 1, 1, "Fuze",  dualboot_fuze,     sizeof(dualboot_fuze),     "fuze", 43 },
    [MODEL_M200V4]  = { 4, 1, "m200",  dualboot_m200v4,   sizeof(dualboot_m200v4),   "m2v4", 42 },
    [MODEL_CLIPZIP] = { 1, 2, "ClipZip", dualboot_clipzip, sizeof(dualboot_clipzip), "clzp", 79 },
};


/* Checksums of unmodified original firmwares - for safety, and device
   detection */
static struct md5sums sansasums[] = {
    /* NOTE: Different regional versions of the firmware normally only
             differ in the filename - the md5sums are identical */

    /*   model       version    md5                        */
    { MODEL_E200V2, "3.01.11", "e622ca8cb6df423f54b8b39628a1f0a3" },
    { MODEL_E200V2, "3.01.14", "2c1d0383fc3584b2cc83ba8cc2243af6" },
    { MODEL_E200V2, "3.01.16", "12563ad71b25a1034cf2092d1e0218c4" },

    { MODEL_FUZE,   "1.01.11", "cac8ffa03c599330ac02c4d41de66166" },
    { MODEL_FUZE,   "1.01.15", "df0e2c1612727f722c19a3c764cff7f2" },
    { MODEL_FUZE,   "1.01.22", "5aff5486fe8dd64239cc71eac470af98" },
    { MODEL_FUZE,   "1.02.26", "7c632c479461c48c8833baed74eb5e4f" },
    { MODEL_FUZE,   "1.02.28", "5b34260f6470e75f702a9c6825471752" },
    { MODEL_FUZE,   "1.02.31", "66d01b37462a5ef7ccc6ad37188b4235" },

    { MODEL_C200V2, "3.02.05", "b6378ebd720b0ade3fad4dc7ab61c1a5" },

    { MODEL_M200V4, "4.00.45", "82e3194310d1514e3bbcd06e84c4add3" },
    { MODEL_M200V4, "4.01.08-A", "fc9dd6116001b3e6a150b898f1b091f0" },
    { MODEL_M200V4, "4.01.08-E", "d3fb7d8ec8624ee65bc99f8dab0e2369" },

    { MODEL_CLIP,   "1.01.17", "12caad785d506219d73f538772afd99e" },
    { MODEL_CLIP,   "1.01.18", "d720b266bd5afa38a198986ef0508a45" },
    { MODEL_CLIP,   "1.01.20", "236d8f75189f468462c03f6d292cf2ac" },
    { MODEL_CLIP,   "1.01.29", "c12711342169c66e209540cd1f27cd26" },
    { MODEL_CLIP,   "1.01.30", "f2974d47c536549c9d8259170f1dbe4d" },
    { MODEL_CLIP,   "1.01.32", "d835d12342500732ffb9c4ee54abec15" },
    { MODEL_CLIP,   "1.01.35", "b4d0edb3b8f2a4e8eee0a344f7f8e480" },

    { MODEL_CLIPV2, "2.01.16", "c57fb3fcbe07c2c9b360f060938f80cb" },
    { MODEL_CLIPV2, "2.01.32", "0ad3723e52022509089d938d0fbbf8c5" },
    { MODEL_CLIPV2, "2.01.35", "a3cbbd22b9508d7f8a9a1a39acc342c2" },

    { MODEL_CLIPPLUS, "01.02.09", "656d38114774c2001dc18e6726df3c5d" },
    { MODEL_CLIPPLUS, "01.02.13", "5f89872b79ef440b0e5ee3a7a44328b2" },
    { MODEL_CLIPPLUS, "01.02.15", "680a4f521e790ad25b93b1b16f3a207d" },
    { MODEL_CLIPPLUS, "01.02.16", "055a53de1dfb09f6cb71c504ad48bd13" },
    { MODEL_CLIPPLUS, "01.02.18", "80b547244438b113e2a55ff0305f12c0" },

    { MODEL_FUZEV2, "2.01.17", "8b85fb05bf645d08a4c8c3e344ec9ebe" },
    { MODEL_FUZEV2, "2.02.26", "d4f6f85c3e4a8ea8f2e5acc421641801" },
    { MODEL_FUZEV2, "2.03.31", "74fb197ccd51707388f3b233402186a6" },
    { MODEL_FUZEV2, "2.03.33", "1599cc73d02ea7fe53fe2d4379c24b66" },
    
    { MODEL_CLIPZIP, "1.01.12", "45adea0873326b5af34f096e5c402f78" },
    { MODEL_CLIPZIP, "1.01.15", "f62af954334cd9ba1a87a7fa58ec6074" },
    { MODEL_CLIPZIP, "1.01.17", "27bcb343d6950f35dc261629e22ba60c" },
    { MODEL_CLIPZIP, "1.01.18", "ef16aa9e02b49885ebede5aa149502e8" },
    { MODEL_CLIPZIP, "1.01.20", "d88c8977cc6a952d3f51ece105869d97" },
};

#define NUM_MD5S (sizeof(sansasums)/sizeof(sansasums[0]))

static unsigned int model_memory_size(int model)
{
    /* The OF boots with IRAM (320kB) mapped at 0x0 */

    if(model == MODEL_CLIPV2)
    {
        /* The decompressed Clipv2 OF is around 380kB.
         * Let's use the full IRAM (1MB on AMSv2)
         */
        return 1 << 20;
    }
    else
    {
        /* The IRAM is 320kB on AMSv1, and 320 will be enough on Fuzev1/Clip+ */
        return 320 << 10;
    }
}

int firmware_revision(int model)
{
    return ams_identity[model].fw_revision;
}

static off_t filesize(int fd)
{
    struct stat buf;

    if (fstat(fd, &buf) < 0) {
        perror("[ERR]  Checking filesize of input file");
        return -1;
    } else {
        return(buf.st_size);
    }
}

static uint32_t get_uint32le(unsigned char* p)
{
    return p[0] | (p[1] << 8) | (p[2] << 16) | (p[3] << 24);
}

static uint32_t get_uint32be(unsigned char* p)
{
    return (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
}

static void put_uint32le(unsigned char* p, uint32_t x)
{
    p[0] = x & 0xff;
    p[1] = (x >> 8) & 0xff;
    p[2] = (x >> 16) & 0xff;
    p[3] = (x >> 24) & 0xff;
}

void calc_MD5(unsigned char* buf, int len, char *md5str)
{
    int i;
    md5_context ctx;
    unsigned char md5sum[16];

    md5_starts(&ctx);
    md5_update(&ctx, buf, len);
    md5_finish(&ctx, md5sum);

    for (i = 0; i < 16; ++i)
        sprintf(md5str + 2*i, "%02x", md5sum[i]);
}

/* Calculate a simple checksum used in Sansa Original Firmwares */
static uint32_t calc_checksum(unsigned char* buf, uint32_t n)
{
    uint32_t sum = 0;
    uint32_t i;

    for (i=0;i<n;i+=4)
        sum += get_uint32le(buf + i);

    return sum;
}

/* Compress using nrv2e algorithm : Thumb decompressor fits in 168 bytes ! */
static unsigned char* uclpack(unsigned char* inbuf, int insize, int* outsize)
{
    int maxsize;
    unsigned char* outbuf;
    int r;

    /* The following formula comes from the UCL documentation */
    maxsize = insize + (insize / 8) + 256;

    /* Allocate some memory for the output buffer */
    outbuf = malloc(maxsize);

    if (outbuf == NULL)
        return NULL;

    r = ucl_nrv2e_99_compress(
            (const ucl_bytep) inbuf,
            (ucl_uint) insize,
            (ucl_bytep) outbuf,
            (ucl_uintp) outsize,
            0, 10, NULL, NULL);

    if (r != UCL_E_OK || *outsize > maxsize) {
        /* this should NEVER happen, and implies memory corruption */
        fprintf(stderr, "internal error - compression failed: %d\n", r);
        free(outbuf);
        return NULL;
    }

    return outbuf;
}

#define ERROR(format, ...) \
    do { \
        snprintf(errstr, errstrsize, format, __VA_ARGS__); \
        goto error; \
    } while(0)

/* Loads a Sansa AMS Original Firmware file into memory */
unsigned char* load_of_file(
        char* filename, int model, off_t* bufsize, struct md5sums *sum,
        int* firmware_size, unsigned char** of_packed,
        int* of_packedsize, char* errstr, int errstrsize)
{
    int fd;
    unsigned char* buf =NULL;
    off_t n;
    unsigned int i=0;
    uint32_t checksum;
    unsigned int last_word;

    fd = open(filename, O_RDONLY|O_BINARY);
    if (fd < 0)
        ERROR("[ERR]  Could not open %s for reading\n", filename);

    *bufsize = filesize(fd);

    buf = malloc(*bufsize);
    if (buf == NULL)
        ERROR("[ERR]  Could not allocate memory for %s\n", filename);

    n = read(fd, buf, *bufsize);

    if (n != *bufsize)
        ERROR("[ERR]  Could not read file %s\n", filename);

    /* check the file */

    /* Calculate MD5 checksum of OF */
    calc_MD5(buf, *bufsize, sum->md5);

    while ((i < NUM_MD5S) && (strcmp(sansasums[i].md5, sum->md5) != 0))
        i++;

    if (i < NUM_MD5S) {
        *sum = sansasums[i];
        if(sum->model != model) {
            ERROR("[ERR]  OF File provided is %sv%d version %s, not for %sv%d\n",
                ams_identity[sum->model].model_name, ams_identity[sum->model].hw_revision,
                sum->version, ams_identity[model].model_name, ams_identity[model].hw_revision
            );
        }
    } else {
        /* OF unknown, give a list of tested versions for the requested model */

        char tested_versions[100];
        tested_versions[0] = '\0';

        for (i = 0; i < NUM_MD5S ; i++)
            if (sansasums[i].model == model) {
                if (tested_versions[0] != '\0') {
                    strncat(tested_versions, ", ",
                        sizeof(tested_versions) - strlen(tested_versions) - 1);
                }
                strncat(tested_versions, sansasums[i].version,
                    sizeof(tested_versions) - strlen(tested_versions) - 1);
            }

        ERROR("[ERR]  Original firmware unknown, please try another version."
              " Tested %sv%d versions are: %s\n",
              ams_identity[model].model_name, ams_identity[model].hw_revision, tested_versions);
    }

    /* TODO: Do some more sanity checks on the OF image. Some images (like
       m200v4) dont have a checksum at the end, only padding (0xdeadbeef). */
    last_word = *bufsize - 4;
    checksum = get_uint32le(buf + last_word);
    if (checksum != 0xefbeadde && checksum != calc_checksum(buf, last_word))
        ERROR("%s", "[ERR]  Whole file checksum failed\n");

    if (ams_identity[sum->model].bootloader == NULL)
        ERROR("[ERR]  Unsupported model - \"%s\"\n", ams_identity[sum->model].model_name);

    /* Get the firmware size */
    if (ams_identity[sum->model].fw_revision == 1)
        *firmware_size = get_uint32le(&buf[0x0c]);
    else if (ams_identity[sum->model].fw_revision == 2)
        *firmware_size = get_uint32le(&buf[0x10]);

    /* Compress the original firmware image */
    *of_packed = uclpack(buf + 0x400, *firmware_size, of_packedsize);
    if (*of_packed == NULL)
        ERROR("[ERR]  Could not compress %s\n", filename);

    return buf;

error:
    free(buf);
    return NULL;
}

/* Loads a rockbox bootloader file into memory */
unsigned char* load_rockbox_file(
            char* filename, int *model, int* bufsize, int* rb_packedsize,
            char* errstr, int errstrsize)
{
    int fd;
    unsigned char* buf = NULL;
    unsigned char* packed = NULL;
    unsigned char header[8];
    uint32_t sum;
    off_t n;
    int i;

    fd = open(filename, O_RDONLY|O_BINARY);
    if (fd < 0)
        ERROR("[ERR]  Could not open %s for reading\n", filename);

    /* Read Rockbox header */
    n = read(fd, header, sizeof(header));
    if (n != sizeof(header))
        ERROR("[ERR]  Could not read file %s\n", filename);

    for(*model = 0; *model < NUM_MODELS; (*model)++)
        if (memcmp(ams_identity[*model].rb_model_name, header + 4, 4) == 0)
            break;

    if(*model == NUM_MODELS)
        ERROR("[ERR]  Model name \"%4.4s\" unknown. Is this really a rockbox bootloader?\n", header + 4);

    *bufsize = filesize(fd) - sizeof(header);

    buf = malloc(*bufsize);
    if (buf == NULL)
        ERROR("[ERR]  Could not allocate memory for %s\n", filename);

    n = read(fd, buf, *bufsize);

    if (n != *bufsize)
        ERROR("[ERR]  Could not read file %s\n", filename);

    /* Check checksum */
    sum = ams_identity[*model].rb_model_num;
    for (i = 0; i < *bufsize; i++) {
         /* add 8 unsigned bits but keep a 32 bit sum */
         sum += buf[i];
    }

    if (sum != get_uint32be(header))
        ERROR("[ERR]  Checksum mismatch in %s\n", filename);

    packed = uclpack(buf, *bufsize, rb_packedsize);
    if(packed == NULL)
        ERROR("[ERR]  Could not compress %s\n", filename);

    free(buf);
    return packed;

error:
    free(buf);
    return NULL;
}

#undef ERROR

/* Patches a Sansa AMS Original Firmware file */
void patch_firmware(
        int model, int fw_revision, int firmware_size, unsigned char* buf,
        int len, unsigned char* of_packed, int of_packedsize,
        unsigned char* rb_packed, int rb_packedsize)
{
    unsigned char *p;
    uint32_t sum, filesum;
    uint32_t ucl_dest;
    unsigned int i;

    /* Zero the original firmware area - not needed, but helps debugging */
    memset(buf + 0x600, 0, firmware_size);

    /* Insert dual-boot bootloader at offset 0x200, we preserve the OF
     * version string located between 0x0 and 0x200 */
    memcpy(buf + 0x600, ams_identity[model].bootloader, ams_identity[model].bootloader_size);

    /* Insert vectors, they won't overwrite the OF version string */
    static const uint32_t goto_start    = 0xe3a0fc02; // mov pc, #0x200
    static const uint32_t infinite_loop = 0xeafffffe; // 1: b 1b
    /* ALL vectors: infinite loop */
    for (i=0; i < 8; i++)
        put_uint32le(buf + 0x400 + 4*i, infinite_loop);
    /* Now change only the interesting vectors */
    /* Reset/SWI vectors: branch to our dualboot code at 0x200 */
    put_uint32le(buf + 0x400 + 4*0, goto_start); // Reset
    put_uint32le(buf + 0x400 + 4*2, goto_start); // SWI

    /* We are filling the firmware buffer backwards from the end */
    p = buf + 0x400 + firmware_size;

    /* 1 - UCL unpack function */
    p -= sizeof(nrv2e_d8);
    memcpy(p, nrv2e_d8, sizeof(nrv2e_d8));

    /* 2 - Compressed copy of original firmware */
    p -= of_packedsize;
    memcpy(p, of_packed, of_packedsize);

    /* 3 - Compressed copy of Rockbox bootloader */
    p -= rb_packedsize;
    memcpy(p, rb_packed, rb_packedsize);

    /* Write the locations of the various images to the variables at the
       start of the dualboot image - we save the location of the last byte
       in each image, along with the size in bytes */

    /* UCL unpack function */
    put_uint32le(&buf[0x604], firmware_size - 1);
    put_uint32le(&buf[0x608], sizeof(nrv2e_d8));

    /* Compressed original firmware image */
    put_uint32le(&buf[0x60c], firmware_size - sizeof(nrv2e_d8) - 1);
    put_uint32le(&buf[0x610], of_packedsize);

    /* Compressed Rockbox image */
    put_uint32le(&buf[0x614], firmware_size - sizeof(nrv2e_d8) - of_packedsize
            - 1);
    put_uint32le(&buf[0x618], rb_packedsize);

    ucl_dest = model_memory_size(model) - 1; /* last byte of memory */
    put_uint32le(&buf[0x61c], ucl_dest);

    /* Update the firmware block checksum */
    sum = calc_checksum(buf + 0x400, firmware_size);

    if (fw_revision == 1) {
        put_uint32le(&buf[0x04], sum);
        put_uint32le(&buf[0x204], sum);
    } else if (fw_revision == 2) {
        put_uint32le(&buf[0x08], sum);
        put_uint32le(&buf[0x208], sum);

        /* Update the header checksums */
        put_uint32le(&buf[0x1fc], calc_checksum(buf, 0x1fc));
        put_uint32le(&buf[0x3fc], calc_checksum(buf + 0x200, 0x1fc));
    }

    /* Update the whole-file checksum */
    filesum = 0;
    for (i=0;i < (unsigned)len - 4; i+=4)
        filesum += get_uint32le(&buf[i]);

    put_uint32le(buf + len - 4, filesum);
}

/* returns != 0 if the firmware can be safely patched */
int check_sizes(int model, int rb_packed_size, int rb_unpacked_size,
        int of_packed_size, int of_unpacked_size, int *total_size,
        char *errstr, int errstrsize)
{
    /* XXX: we keep the first 0x200 bytes block unmodified, we just replace
     * the ARM vectors */
    unsigned int packed_size = ams_identity[model].bootloader_size + sizeof(nrv2e_d8) +
            of_packed_size + rb_packed_size + 0x200;

    /* how much memory is available */
    unsigned int memory_size = model_memory_size(model);

    /* the memory used when unpacking the OF */
    unsigned int ram_of = sizeof(nrv2e_d8) + of_packed_size + of_unpacked_size;

    /* the memory used when unpacking the bootloader */
    unsigned int ram_rb = sizeof(nrv2e_d8) + rb_packed_size + rb_unpacked_size;

    *total_size = packed_size;

#define ERROR(format, ...) \
    do { \
        snprintf(errstr, errstrsize, format, __VA_ARGS__); \
        return 0; \
    } while(0)

    /* will packed data fit in the OF file ? */
    if(packed_size > of_unpacked_size)
        ERROR(
            "[ERR]  Packed data (%d bytes) doesn't fit in the firmware "
            "(%d bytes)\n", packed_size, of_unpacked_size
            );

    else if(ram_rb > memory_size)
        ERROR("[ERR]  Rockbox can't be unpacked at runtime, needs %d bytes "
            "of memory and only %d available\n", ram_rb, memory_size
            );

    else if(ram_of > memory_size)
        ERROR("[ERR]  OF can't be unpacked at runtime, needs %d bytes "
            "of memory and only %d available\n", ram_of, memory_size
            );

    return 1;

#undef ERROR
}