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cell: Fix off-by-one error in spu_dcache_fetch_unaligned

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This time the off-by-one error caused an extra qword to be fetched
under certain circumstances when the source ea was not qword aligned.
This commit is contained in:
Ian Romanick 2008-02-22 17:51:55 -08:00
parent a63fd641a0
commit 2efa7e9489
1 changed files with 31 additions and 17 deletions
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48
src/gallium/drivers/cell/spu/spu_dcache.c
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@ -49,43 +49,57 @@
/**
* Fetch between arbitrary number of bytes from an unaligned address
*
* \param dst Destination data buffer
* \param ea Main memory effective address of source data
* \param size Number of bytes to read
*
* \warning
* As is hinted by the type of the \c dst pointer, this function writes
* multiples of 16-bytes.
*/
void
spu_dcache_fetch_unaligned(qword *dst, unsigned ea, unsigned size)
{
const int shift = ea & 0x0f;
const unsigned aligned_start_ea = ea & ~0x0f;
const unsigned aligned_end_ea = ROUNDUP16(ea + size);
const unsigned num_entries = (aligned_end_ea - aligned_start_ea) / 16;
const unsigned read_size = ROUNDUP16(size + shift);
const unsigned last_read = ROUNDUP16(ea + size);
const qword *const last_write = dst + (ROUNDUP16(size) / 16);
unsigned i;
if (shift == 0) {
/* Data is already aligned. Fetch directly into the destination buffer.
*/
for (i = 0; i < num_entries; i++) {
dst[i] = cache_rd(data, ea + (i * 16));
for (i = 0; i < size; i += 16) {
*(dst++) = cache_rd(data, ea + i);
}
} else {
qword tmp[2] ALIGN16_ATTRIB;
qword hi;
tmp[0] = cache_rd(data, (ea & ~0x0f));
for (i = 0; i < (num_entries & ~1); i++) {
const unsigned curr = i & 1;
const unsigned next = curr ^ 1;
/* Please exercise extreme caution when modifying this code. This code
* must not read past the end of the page containing the source data,
* and it must not write more than ((size + 15) / 16) qwords to the
* destination buffer.
*/
ea &= ~0x0f;
hi = cache_rd(data, ea);
for (i = 16; i < read_size; i += 16) {
qword lo = cache_rd(data, ea + i);
tmp[next] = cache_rd(data, (ea & ~0x0f) + (next * 16));
dst[i] = si_or((qword) spu_slqwbyte(tmp[curr], shift),
(qword) spu_rlmaskqwbyte(tmp[next], shift - 16));
*(dst++) = si_or((qword) spu_slqwbyte(hi, shift),
(qword) spu_rlmaskqwbyte(lo, shift - 16));
hi = lo;
}
if (i < num_entries) {
dst[i] = si_or((qword) spu_slqwbyte(tmp[(i & 1)], shift),
si_il(0));
if (dst != last_write) {
*(dst++) = si_or((qword) spu_slqwbyte(hi, shift), si_il(0));
}
}
ASSERT((ea + i) == last_read);
ASSERT(dst == last_write);
}