Revision as of 20:00, 25 February 2014 view source Pancakes (talk \| contribs) 294 edits m finally got it right ← Older edit		Revision as of 23:13, 25 February 2014 view source Pancakes (talk \| contribs) 294 edits m changed statement meaning from "should" to "need" for usage of LIBGCC and make it more attraction for people to check out links about cross-compiling and libgcc than forum links (which might cause them to try to go around using libgcc) Newer edit →
Line 249: ==Coding Gotchas== ===== Missing Division Functions (__aeabi_uidivmod, __aeabi_idiv) / No Division Support ===== This is caused by using GCC and not linking with ''libgcc''. ~~It is~~You ''~~highly~~NEED TO'' ~~recommended that you~~ link with ''libgcc'' when using GCC. For information about why you should link and information about ''libgcc'', read [[Libgcc]] and [[GCC_Cross-Compiler]]. You must also make sure you use the ''libgcc'' that has been compiled for your target machine/architecture/platform. See [[Libgcc]] for more information. You can produce the correct library for GCC by reading [[GCC_Cross-Compiler]]. ====== This section is just if you want a more in depth explanation and discussion. ====== This issue is actually complicated because different CPUs may not support hardware division, support it only through the floating point operations, in thumb mode, in native mode, or a combination. Also, in certain situations you may find it faster or more compact to use different methods because you may be interested in code size or performance. ~~Normally,~~The ''libgcc'' will handle all of these situations and provide the needed symbols, however here are some various sources of information that can give you a more in-depth understanding: <pre> The following links talk about different methods in handling this problem: http://forum.osdev.org/viewtopic.php?f=1&t=23857&p=212244▼ http://stackoverflow.com/questions/8348030/how-does-one-do-integer-signed-or-unsigned-division-on-arm▼ ▲http://forum.osdev.org/viewtopic.php?f=1&t=23857&p=212244 ▲http://stackoverflow.com/questions/8348030/how-does-one-do-integer-signed-or-unsigned-division-on-arm Also, some extra information that maybe useful: http://www.linkedin.com/groups/ARM-cores-hardware-division-85447.S.242517259▼ A discussion about this section, and also at the end an example of LIBGCC's version of the ~~functions~~divide function:▼ ▲http://www.linkedin.com/groups/ARM-cores-hardware-division-85447.S.242517259 http://forum.osdev.org/viewtopic.php?f=8&t=27767▼ ▲A discussion about this section, and also at the end an example of LIBGCC's version of the functions: ▲http://forum.osdev.org/viewtopic.php?f=8&t=27767 The source for LIBGCC and source of the division emulation function: https://github.com/mirrors/gcc/blob/master/libgcc/udivmodsi4.c▼ https://github.com/mirrors/gcc/blob/master/libgcc/~~udivmodsi4.c~~ </pre> ▲https://github.com/mirrors/gcc/blob/master/libgcc/ ===== Unaligned Memory Access And Byte Order ===== {\| border="1px"

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