Introduce countDigits() function for PID and UID field widths #1561
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The GPU_TIME field is now fixed width, and thus there is no need to call Row_updateFieldWidth(). Signed-off-by: Kang-Che Sung <[email protected]>
countDigits() is designed with 64-bit integer input and may be reused for computing field widths of, for example, memory addresses. Signed-off-by: Kang-Che Sung <[email protected]> Co-authored-by: Benny Baumann <[email protected]> Co-authored-by: Odric Roux-Paris <[email protected]>
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| /* Counts the number of digits needed to print "n" with a given base. | ||
| If "n" is zero, returns 1. This function expects small numbers to | ||
| appear often, hence it uses a O(log(n)) time algorithm. */ | ||
| size_t countDigits(size_t n, size_t base) { |
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This question is a bit pedantic here. Since we plan to use countDigits for memory address, too, the more proper type for this function's input would be uintptr_t and not size_t. May I ask, is it better for this function's type be changed to uintptr_t to better indicate the intent? The output type can remain size_t as I see no reason for changing it.
Technical thing here: size_t and uintptr_t do not necessarily have the same size. In the C standard's sense, sizeof(size_t) <= sizeof(uintptr_t). On flat memory systems they are indeed the same size, but on other platforms (e.g. segmented memory) size_t can be defined to be narrower than uintptr_t.
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Use uint64_t and there's no problem (except for some potential upcasts for clang).
But I don't think we need to change this here; size_t is fine.
The countDigits function was proposed in #1270 (@BenBE and @MrCirdo). And I make PID and UID field widths the first users of this new function.