From 0997bbbaacc1be7b0bea678d6e021fb67e3ca63e Mon Sep 17 00:00:00 2001 From: Danny Robson Date: Wed, 4 Jan 2017 22:38:15 +1100 Subject: [PATCH] endian: add signed byteswap --- endian.hpp | 27 ++++++++++++++++++++++----- 1 file changed, 22 insertions(+), 5 deletions(-) diff --git a/endian.hpp b/endian.hpp index f2777775..aef5087e 100644 --- a/endian.hpp +++ b/endian.hpp @@ -35,12 +35,29 @@ namespace util { constexpr T bswap (T); - //template <> constexpr int8_t bswap ( int8_t v) { return v; } - //template <> constexpr int16_t bswap (int16_t v) { return __builtin_bswap16 (v); } - //template <> constexpr int32_t bswap (int32_t v) { return __builtin_bswap32 (v); } - //template <> constexpr int64_t bswap (int64_t v) { return __builtin_bswap64 (v); } + // CXX: Update using "if constexpr" when available. It doesn't seem to be + // worth the dicking about to use enable_if_t to differentiate the + // signed/unsigned cases. + #define SIGNED_BSWAP(S) \ + template <> \ + constexpr \ + int##S##_t \ + bswap (int##S##_t v) { \ + const union { \ + int##S##_t s; \ + uint##S##_t u; \ + } vu = { v }; \ + \ + return __builtin_bswap##S (vu.u); \ + } + + SIGNED_BSWAP(16) + SIGNED_BSWAP(32) + SIGNED_BSWAP(64) + + template <> constexpr int8_t bswap ( int8_t v) { return v; } + template <> constexpr uint8_t bswap (uint8_t v) { return v; } - template <> constexpr uint8_t bswap ( uint8_t v) { return v; } template <> constexpr uint16_t bswap (uint16_t v) { return __builtin_bswap16 (v); } template <> constexpr uint32_t bswap (uint32_t v) { return __builtin_bswap32 (v); } template <> constexpr uint64_t bswap (uint64_t v) { return __builtin_bswap64 (v); }