From cf42bdca5a0ddde866b91d3b44f64f495c2357f5 Mon Sep 17 00:00:00 2001 From: Chris Kay Date: Mon, 24 Mar 2014 11:53:46 +0000 Subject: [PATCH] Refactored and added comments --- sprout/net/endian.hpp | 94 ++++++++++++++++++++++++++++++++++--------- 1 file changed, 76 insertions(+), 18 deletions(-) diff --git a/sprout/net/endian.hpp b/sprout/net/endian.hpp index b17bea77..48592352 100644 --- a/sprout/net/endian.hpp +++ b/sprout/net/endian.hpp @@ -18,62 +18,109 @@ namespace sprout { namespace net { namespace detail { + /* + * lshift_by + * Left shift 'val' by 'n' bytes + */ template - SPROUT_CONSTEXPR T lshift(T val, uint_fast8_t byte) { - return val << (byte * 8); + SPROUT_CONSTEXPR T lshift_by(T val, uint_fast8_t n) { + return val << (n * 8); } + /* + * rshift_by + * Right shift 'val' by 'n' bytes + */ template - SPROUT_CONSTEXPR T rshift(T val, uint_fast8_t byte) { - return val >> (byte * 8); + SPROUT_CONSTEXPR T rshift_by(T val, uint_fast8_t n) { + return val >> (n * 8); } + /* + * mask_t + * Mask 'n'th byte + */ template - SPROUT_CONSTEXPR T mask(uint_fast8_t byte) { - return lshift(T(0xFF), byte); + SPROUT_CONSTEXPR T mask_at(uint_fast8_t n) { + return lshift_by(T(0xFF), n); } + /* + * byte_at + * Get 'n'th byte from 'val' + */ template - SPROUT_CONSTEXPR T byte_at(T val, uint_fast8_t byte) { - return rshift((val & mask(byte)), byte); + SPROUT_CONSTEXPR T byte_at(T val, uint_fast8_t n) { + return rshift_by((val & mask_at(n)), n); } + /* + * replace_at + * Replace, in 'val', 'n'th byte with 'byte_val' + */ template - SPROUT_CONSTEXPR T overwrite(T val, uint8_t byte_val, uint_fast8_t to) { - return (val & ~mask(to)) | lshift(T(byte_val), to); + SPROUT_CONSTEXPR T replace_at(T val, uint8_t byte_val, uint_fast8_t n) { + return (val & ~mask_at(n)) | lshift_by(T(byte_val), n); } + /* + * copy + * Copy, in 'val', byte at index 'from' to byte at index 'to' + */ template - SPROUT_CONSTEXPR T move(T val, uint_fast8_t from, uint_fast8_t to) { - return overwrite(val, byte_at(val, from), to); + SPROUT_CONSTEXPR T copy(T val, uint_fast8_t from, uint_fast8_t to) { + return replace_at(val, byte_at(val, from), to); } + /* + * swap + * Swap, in 'val', byte at index 'n1' with byte at index 'n2' + */ template - SPROUT_CONSTEXPR T swap(T val, uint_fast8_t byte1, uint_fast8_t byte2) { - return overwrite(move(val, byte1, byte2), byte_at(val, byte2), byte1); + SPROUT_CONSTEXPR T swap(T val, uint_fast8_t n1, uint_fast8_t n2) { + return replace_at(copy(val, n1, n2), byte_at(val, n2), n1); } + /* + * reverse_impl + * Swap, in 'val', byte at index 'n1' with byte at index 'n2' in 'val', increment n1, decrement n2 until n1 > n2 + */ template - SPROUT_CONSTEXPR T reverse_impl(T val, uint_fast8_t byte1, uint_fast8_t byte2) { - return byte1 > byte2 ? val : reverse_impl(swap(val, byte1, byte2), byte1 + 1, byte2 - 1); + SPROUT_CONSTEXPR T reverse_impl(T val, uint_fast8_t n1, uint_fast8_t n2) { + return n1 > n2 ? val : reverse_impl(swap(val, n1, n2), n1 + 1, n2 - 1); } + /* + * reverse + * Reverse 'val' + */ template SPROUT_CONSTEXPR T reverse(T val) { return reverse_impl(val, 0, sizeof(T) - 1); } + /* + * reverse_words_impl + * Swap, in 'val', byte at index 'n' - 1 with byte at index 'n' - 2, decrement n by 2 until n == 0 + */ template - SPROUT_CONSTEXPR T reverse_words_impl(T val, uint_fast8_t byte) { - return byte == 0 ? val : reverse_words_impl(swap(val, byte - 1, byte - 2), byte - 2); + SPROUT_CONSTEXPR T reverse_words_impl(T val, uint_fast8_t n) { + return n == 0 ? val : reverse_words_impl(swap(val, n - 1, n - 2), n - 2); } + /* + * reverse_words + * Reverse each word in 'val' + */ template SPROUT_CONSTEXPR T reverse_words(T val) { return reverse_words_impl(val, sizeof(T)); } } + // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3620.pdf + // template<> + // constexpr unsigned-integral hton(unsigned-integral host) template SPROUT_CONSTEXPR T hton(T host) { #if defined(BOOST_BIG_ENDIAN) @@ -85,6 +132,9 @@ namespace sprout { #endif } + // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3620.pdf + // template<> + // constexpr unsigned-integral ntoh(unsigned-integral net) template SPROUT_CONSTEXPR T ntoh(T net) { #if defined(BOOST_BIG_ENDIAN) @@ -96,18 +146,26 @@ namespace sprout { #endif } + // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3620.pdf + // uint32_t htonl(uint32_t host32) SPROUT_CONSTEXPR uint32_t htonl(uint32_t host32) { return hton(host32); } + // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3620.pdf + // uint16_t htons(uint16_t host16) SPROUT_CONSTEXPR uint16_t htons(uint16_t host16) { return hton(host16); } + // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3620.pdf + // uint32_t ntohl(uint32_t net32) SPROUT_CONSTEXPR uint32_t ntohl(uint32_t net32) { return ntoh(net32); } + // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3620.pdf + // uint16_t ntohs(uint32_t net16) SPROUT_CONSTEXPR uint16_t ntohs(uint16_t net16) { return ntoh(net16); }