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Make use of std::rotl (C++20) if available

This commit is contained in:
Carles Fernandez 2020-06-16 12:22:37 +02:00
parent 094f8f2ee9
commit 771fbf1365
No known key found for this signature in database
GPG Key ID: 4C583C52B0C3877D
3 changed files with 40 additions and 10 deletions
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20
CMakeLists.txt
View File

@ -833,7 +833,6 @@ endif()
# Detect availability of std::span
################################################################################
unset(has_span CACHE)
include(CheckCXXSourceCompiles)
check_cxx_source_compiles("
#include <span>
int main()
@ -843,6 +842,25 @@ check_cxx_source_compiles("
################################################################################
# Detect availability of std::rotl
################################################################################
unset(has_rotl CACHE)
if(CMAKE_CXX_STANDARD VERSION_GREATER 17)
check_cxx_source_compiles("
#include <bit>
#include <cstdint>
int main()
{
std::uint8_t i = 0b00011101;
auto k = std::rotl(i,0);
}"
has_rotl
)
endif()
################################################################################
# Detect availability of std::put_time (Workaround for gcc < 5.0)
################################################################################

6
src/algorithms/telemetry_decoder/gnuradio_blocks/CMakeLists.txt
View File

@ -68,6 +68,12 @@ if(GNURADIO_USES_STD_POINTERS)
)
endif()
if(has_rotl)
target_compile_definitions(telemetry_decoder_gr_blocks
PRIVATE -DCOMPILER_HAS_ROTL=1
)
endif()
if(ENABLE_CLANG_TIDY)
if(CLANG_TIDY_EXE)
set_target_properties(telemetry_decoder_gr_blocks

24
src/algorithms/telemetry_decoder/gnuradio_blocks/gps_l1_ca_telemetry_decoder_gs.cc
View File

@ -33,8 +33,14 @@
#include <memory> // for shared_ptr
#ifndef _rotl
auto _rotl = [](auto x, auto n) { return (((x) << (n)) ^ ((x) >> (32 - (n)))); }; // Used in the parity check algorithm
#ifdef COMPILER_HAS_ROTL
#include <bit>
namespace my_rotl = std;
#else
namespace my_rotl
{
auto rotl = [](auto x, auto n) { return (((x) << (n)) ^ ((x) >> (32 - (n)))); }; // Used in the parity check algorithm
}
#endif
@ -138,15 +144,15 @@ bool gps_l1_ca_telemetry_decoder_gs::gps_word_parityCheck(uint32_t gpsword)
// check algorithm described in IS-GPS-200K. This avoids lengthy shift-
// and-xor loops.
d1 = gpsword & 0xFBFFBF00U;
d2 = _rotl(gpsword, 1U) & 0x07FFBF01U;
d3 = _rotl(gpsword, 2U) & 0xFC0F8100U;
d4 = _rotl(gpsword, 3U) & 0xF81FFE02U;
d5 = _rotl(gpsword, 4U) & 0xFC00000EU;
d6 = _rotl(gpsword, 5U) & 0x07F00001U;
d7 = _rotl(gpsword, 6U) & 0x00003000U;
d2 = my_rotl::rotl(gpsword, 1U) & 0x07FFBF01U;
d3 = my_rotl::rotl(gpsword, 2U) & 0xFC0F8100U;
d4 = my_rotl::rotl(gpsword, 3U) & 0xF81FFE02U;
d5 = my_rotl::rotl(gpsword, 4U) & 0xFC00000EU;
d6 = my_rotl::rotl(gpsword, 5U) & 0x07F00001U;
d7 = my_rotl::rotl(gpsword, 6U) & 0x00003000U;
t = d1 ^ d2 ^ d3 ^ d4 ^ d5 ^ d6 ^ d7;
// Now XOR the 5 6-bit fields together to produce the 6-bit final result.
parity = t ^ _rotl(t, 6U) ^ _rotl(t, 12U) ^ _rotl(t, 18U) ^ _rotl(t, 24U);
parity = t ^ my_rotl::rotl(t, 6U) ^ my_rotl::rotl(t, 12U) ^ my_rotl::rotl(t, 18U) ^ my_rotl::rotl(t, 24U);
parity = parity & 0x3FU;
if (parity == (gpsword & 0x3FU))
{