[Pixman] [PATCH 0/3] Test negative strides

Siarhei Siamashka siarhei.siamashka at gmail.com
Thu Sep 26 15:01:22 PDT 2013

On Thu, 12 Sep 2013 14:07:22 -0400
"Søren Sandmann Pedersen" <sandmann at cs.au.dk> wrote:

> Pixman has support for negative strides, but up until now, only
> stress-test has actually tested it. The following patches add testing
> of negative strides to several of the test programs. It appears that
> everything actually works fine with negative strides on x86, but it
> would be helpful if people can test on other architectures.
> In particular, the unsigned byte_stride used in arm_simd_fill() looks
> wrong to me, though I'm not sure if arm_simd_fill() is actually hit by
> any of test cases.

Yes, it looks (and is) wrong, but still works on ARM. The two's
complement representation of signed numbers nicely provides identical
results for addition, subtraction and multiplication even if signed
and unsigned types are mixed as long as the operands and the result
have the same width.

But something unexpectedly broke on PowerPC and maybe other big
endian systems after the following commit:

PASS: prng-test
PASS: a1-trap-test
PASS: pdf-op-test
PASS: region-test
PASS: region-translate-test
PASS: combiner-test
PASS: pixel-test
PASS: fetch-test
rotate test failed! (checksum=FE55FCE8, expected 81E9EC2F)
FAIL: rotate-test
PASS: oob-test
PASS: infinite-loop
PASS: trap-crasher
PASS: alpha-loop
PASS: scaling-crash-test
PASS: scaling-helpers-test
PASS: gradient-crash-test
region_contains test passed (checksum=548E0F3F)
PASS: region-contains-test
PASS: alphamap
matrix test passed (checksum=BEBF98C3)
PASS: matrix-test
PASS: stress-test
composite traps test failed! (checksum=2DA2285F, expected AF41D210)
FAIL: composite-traps-test
blitters test failed! (checksum=D486E3F7, expected AC8FDA98)
FAIL: blitters-test
glyph test passed (checksum=FA478A79)
PASS: glyph-test
scaling test failed! (checksum=F18FC96A, expected 92E0F068)
FAIL: scaling-test
affine test failed! (checksum=3EE3CE44, expected BE724CFE)
FAIL: affine-test
PASS: composite
5 of 26 tests failed

Best regards,
Siarhei Siamashka

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