Refactored and added comments

This commit is contained in:
Chris Kay 2014-03-24 11:53:46 +00:00
parent 634bd89d9e
commit cf42bdca5a

View file

@ -18,62 +18,109 @@
namespace sprout {
namespace net {
namespace detail {
/*
* lshift_by
* Left shift 'val' by 'n' bytes
*/
template<typename T>
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<typename T>
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<typename T>
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<typename T>
SPROUT_CONSTEXPR T byte_at(T val, uint_fast8_t byte) {
return rshift((val & mask<T>(byte)), byte);
SPROUT_CONSTEXPR T byte_at(T val, uint_fast8_t n) {
return rshift_by((val & mask_at<T>(n)), n);
}
/*
* replace_at
* Replace, in 'val', 'n'th byte with 'byte_val'
*/
template<typename T>
SPROUT_CONSTEXPR T overwrite(T val, uint8_t byte_val, uint_fast8_t to) {
return (val & ~mask<T>(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<T>(n)) | lshift_by(T(byte_val), n);
}
/*
* copy
* Copy, in 'val', byte at index 'from' to byte at index 'to'
*/
template<typename T>
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<typename T>
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<typename T>
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<typename T>
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<typename T>
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<typename T>
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<typename T>
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<typename T>
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);
}