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rolo: simplify parsing scramble header in load_firmware()

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The standard load_firmware() function is used on targets which
use the "scramble -add" method for generating Rockbox binaries.

While it tries to be a bit more generic and allows the CRC/data
offsets to be placed anywhere in the file, there are no targets
which actually need this flexibility, because they are all using
plain old "scramble -add".

So we can actually simplify load_firmware() and remove defines
from the target headers. All the targets used CRC offset = 0 and
data offset = 8, except for a few which I assume never supported
ROLO or were never tested -- eg. samsungyh820: the CRC and data
offsets cannot both be 0.

The actual motivation for this is removing the calls to lseek(),
which can help make bootloaders a tiny bit smaller, as lseek is
typically not used anywhere else in bootloaders.

Change-Id: Ic2d01e5b75a32e88363f085e3e839146a0710bf4
This commit is contained in:
Aidan MacDonald 2024-03-30 15:02:22 +00:00
parent 7dc8d754a2
commit b0a8cacd1d
92 changed files with 4 additions and 532 deletions
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9
firmware/common/rb-loader.c
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@ -58,16 +58,15 @@ static int load_firmware_filename(unsigned char* buf,
goto end;
}
lseek(fd, FIRMWARE_OFFSET_FILE_CRC, SEEK_SET);
if (read(fd, &chksum, 4) < 4)
/* read 32-bit checksum followed by 4-byte model name,
* this is the "scramble -add" header written by tools/scramble */
if (read(fd, buf, 8) < 8)
{
ret = EREAD_CHKSUM_FAILED;
goto end;
}
chksum = betoh32(chksum); /* Rockbox checksums are big-endian */
lseek(fd, FIRMWARE_OFFSET_FILE_DATA, SEEK_SET);
chksum = load_be32(buf); /* Rockbox checksums are big-endian */
if (read(fd, buf, len) < len)
{