Guard some truncating casts with & 0xFF #40
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Does an explicit cast to (unsigned char) also prevent the runtime breakpoint? That would seem clearer and would definitely avoid any unnecessary bitwise AND instructions. |
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No that doesn't prevent it (the truncation is still there, whether the cast is implicit or explicit). If you're concerned about casts not being optimized away I could make e.g. a function or macro narrow_cast which for msvc does the AND but for other toolsets is a no-op. |
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The result of adding two unsigned chars is an int, so assigning this again to unsigned char results in a narrowing cast. Afaik this is well-defined by the standard but code compiled with cl with all runtime checks enabled will trigger a breakpoint when e.g. scanline[i] + recon[i - bytewidth] yields a number > 255. Fix this, and make it clear what's happening, by and'ing with 0xFF (which should be discarded by any sane optimizer anyway).
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The result of adding two unsigned chars is an int, so assigning this again
to unsigned char results in a narrowing cast. Afaik this is well-defined
by the standard but code compiled with cl with all runtime checks enabled
will trigger a breakpoint when e.g. scanline[i] + recon[i - bytewidth]
yields a number > 255. Fix this, and make it clear what's happening, by
and'ing with 0xFF (which should be discarded by any sane optimizer anyway).