[cairo] Speeding up _cairo_fixed_from_double
otaylor at redhat.com
Thu Oct 26 16:40:55 PDT 2006
On Thu, 2006-10-26 at 19:37 -0400, Michael Sweet wrote:
> Daniel Amelang wrote:
> >> Keep in mind that configure-time endian checks are unreliable on
> >> Mac OS X because a single executable may contain objects for multiple
> >> architectures (right now 32+64 bit Intel and PPC)...
> > AFAIK, the existence of fat binaries doesn't interfere with autoconf's
> > job. We're not building fat binaries during the configure stage, and
> > we don't compile to a fat binary. In addition, that would be a general
> > autoconf on OS X issue, not a cairo thing.
> Well, the side effect is that the autoconf test will report the
> endianess of the host you are compiling on. The problem is akin to
> cross-compiling Cairo...
Note that AC_C_BIGENDIAN almost never requires a runtime check:
- Macro: AC_C_BIGENDIAN ([ACTION-IF-TRUE], [ACTION-IF-FALSE],
If words are stored with the most significant byte first (like
Motorola and SPARC CPUs), execute ACTION-IF-TRUE. If words are
stored with the least significant byte first (like Intel and VAX
CPUs), execute ACTION-IF-FALSE.
This macro runs a test-case if endianness cannot be determined
from the system header files. When cross-compiling, the test-case
is not run but grep'ed for some magic values. ACTION-IF-UNKNOWN
is executed if the latter case fails to determine the byte sex of
the host system.
The default for ACTION-IF-TRUE is to define `WORDS_BIGENDIAN'.
The default for ACTION-IF-FALSE is to do nothing. And finally,
the default for ACTION-IF-UNKNOWN is to abort configure and tell
the installer which variable he should preset to bypass this test.
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