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Add a CHS conversion function. It is not used though as we can't generally make 

valid CHS addresses due to not knowing the geometry of the target device
beforehand. So it's mostly just for completeness...


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35717 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Michael Lotz 2010-03-02 01:22:11 +00:00
parent e3c9401739
commit aceebab740
1 changed files with 54 additions and 4 deletions
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58
src/tools/anyboot/anyboot.cpp
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@ -44,6 +44,41 @@ checkError(bool failed, const char *message)
}
void
chsAddressFor(uint32_t offset, uint8_t *address, uint32_t sectorsPerTrack,
uint32_t headsPerCylinder)
{
if (offset >= 1024 * sectorsPerTrack * headsPerCylinder) {
// not encodable, force LBA
address[0] = 0xff;
address[1] = 0xff;
address[2] = 0xff;
return;
}
uint32_t cylinders = 0;
uint32_t heads = 0;
uint32_t sectors = 0;
uint32_t temp = 0;
while (temp * sectorsPerTrack * headsPerCylinder <= offset)
cylinders = temp++;
offset -= (sectorsPerTrack * headsPerCylinder * cylinders);
temp = 0;
while (temp * sectorsPerTrack <= offset)
heads = temp++;
sectors = offset - (sectorsPerTrack * heads) + 1;
address[0] = heads;
address[1] = sectors;
address[1] |= (cylinders >> 2) & 0xc0;
address[2] = cylinders;
}
int
main(int argc, char *argv[])
{
@ -97,11 +132,9 @@ main(int argc, char *argv[])
// construct the partition table
uint8_t partition[16] = {
0x80, // active
0xff, 0xff, 0xff, // CHS start offset
// TODO: we enforce LBA here, maybe not a good idea?
0xff, 0xff, 0xff, // CHS first block (default to LBA)
0xeb, // partition type (BFS)
0xff, 0xff, 0xff, // CHS end offset
// TODO: see above
0xff, 0xff, 0xff, // CHS last block (default to LBA)
0x00, 0x00, 0x00, 0x00, // imageOffset in blocks (written below)
0x00, 0x00, 0x00, 0x00 // imageSize in blocks (written below)
};
@ -109,9 +142,26 @@ main(int argc, char *argv[])
alignment = kBlockSize - 1;
imageSize = (imageSize + alignment) & ~alignment;
// fill in LBA values
uint32_t partitionOffset = (uint32_t)(imageOffset / kBlockSize);
((uint32_t *)partition)[2] = partitionOffset;
((uint32_t *)partition)[3] = (uint32_t)(imageSize / kBlockSize);
#if 0
// while this should basically work, it makes the boot code needlessly
// use chs which has a high potential of failure due to the geometry
// being unknown beforehand (a fixed geometry would be used here).
uint32_t sectorsPerTrack = 63;
uint32_t headsPerCylinder = 255;
// fill in CHS values
chsAddressFor(partitionOffset, &partition[1], sectorsPerTrack,
headsPerCylinder);
chsAddressFor(partitionOffset + (uint32_t)(imageSize / kBlockSize),
&partition[5], sectorsPerTrack, headsPerCylinder);
#endif
ssize_t written = pwrite(outputFile, partition, 16, 512 - 2 - 16 * 4);
checkError(written != 16, "failed to write partition entry");