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crn_defs: fix false positive “out of range subscript” error #83

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crn_defs: fix false positive “out of range subscript” error #83

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22 changes: 22 additions & 0 deletions inc/crn_defs.h
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Original file line number Diff line number Diff line change
Expand Up @@ -225,6 +225,16 @@ struct crn_packed_uint {
}

inline operator unsigned int() const {
#if 0
/* Compilers will expand the template with all conditions and generate
the code for all conditions even if only one condition is usable per
template variant.

Compilers like ICC will raise warnings at compile time and code analysers
like CodeQL will raise warnings when analysing the compiled binary.

See: https://github.com/DaemonEngine/crunch/issues/79 */

switch (N) {
case 1:
return m_buf[0];
Expand All @@ -235,6 +245,18 @@ struct crn_packed_uint {
default:
return (m_buf[0] << 24U) | (m_buf[1] << 16U) | (m_buf[2] << 8U) | (m_buf[3]);
}
#else
/* We can assume the compiler will unroll that inline function for us,
without any range ambiguity, unlike the above trick. */

unsigned int val = 0U;

for (unsigned int i = 0U; i < N; i++) {
val |= m_buf[ i ] << ((N - (i + 1U)) * 8U);
}

return val;
#endif
}

unsigned char m_buf[N];
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