From 301a008cef559fed5ac398c76e54e4c69597e5a3 Mon Sep 17 00:00:00 2001
From: Laurent THOMAS <laurent.thomas@open-cells.com>
Date: Thu, 9 Dec 2021 16:08:34 +0100
Subject: [PATCH] change runtime to compilation time detection of carryless mul

---
 cmake_targets/CMakeLists.txt   |  6 +++---
 openair1/PHY/CODING/crc_byte.c | 24 +++++++++++++++++++-----
 2 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/cmake_targets/CMakeLists.txt b/cmake_targets/CMakeLists.txt
index 826a243a14..6411a0db58 100644
--- a/cmake_targets/CMakeLists.txt
+++ b/cmake_targets/CMakeLists.txt
@@ -294,7 +294,7 @@ else (CMAKE_SYSTEM_PROCESSOR STREQUAL "armv7l")
       set(COMPILATION_AVX2 "False")
     endif()
     if (CPUINFO MATCHES "sse4_1")
-      set(C_FLAGS_PROCESSOR "${C_FLAGS_PROCESSOR} -msse4.1")
+      set(C_FLAGS_PROCESSOR "${C_FLAGS_PROCESSOR} -msse4.1 -mpclmul")
     endif()
     if (CPUINFO MATCHES "ssse3")
       set(C_FLAGS_PROCESSOR "${C_FLAGS_PROCESSOR} -mssse3")
@@ -322,9 +322,9 @@ add_definitions("-DSTDC_HEADERS=1 -DHAVE_SYS_TYPES_H=1 -DHAVE_SYS_STAT_H=1 -DHAV
 set(commonOpts "-pipe -Wno-packed-bitfield-compat -fPIC -Wall -fno-strict-aliasing -rdynamic")
 
 set(CMAKE_C_FLAGS
-  "${CMAKE_C_FLAGS} ${C_FLAGS_PROCESSOR} ${commonOpts} -std=gnu99 -funroll-loops -mpclmul")
+  "${CMAKE_C_FLAGS} ${C_FLAGS_PROCESSOR} ${commonOpts} -std=gnu99 -funroll-loops")
 set(CMAKE_CXX_FLAGS
-  "${CMAKE_CXX_FLAGS} ${C_FLAGS_PROCESSOR}  ${commonOpts} -std=c++11 -mpclmul")
+  "${CMAKE_CXX_FLAGS} ${C_FLAGS_PROCESSOR}  ${commonOpts} -std=c++11")
 
 
 
diff --git a/openair1/PHY/CODING/crc_byte.c b/openair1/PHY/CODING/crc_byte.c
index d2b8f2e2d3..93e3d83151 100644
--- a/openair1/PHY/CODING/crc_byte.c
+++ b/openair1/PHY/CODING/crc_byte.c
@@ -30,10 +30,13 @@
    Modified in June, 2001, to include  the length non multiple of 8
 */
 
+#define USE_INTEL_CRC __SSE4_1__
 
 #include "coding_defs.h"
 #include "assertions.h"
+#ifdef USE_INTEL_CRC 
 #include "crc.h"
+#endif
 /*ref 36-212 v8.6.0 , pp 8-9 */
 /* the highest degree is set by default */
 
@@ -94,6 +97,7 @@ static unsigned short      crc11Table[256];
 static unsigned char       crc8Table[256];
 static unsigned char       crc6Table[256];
 
+#ifdef USE_INTEL_CRC
 static DECLARE_ALIGNED(struct crc_pclmulqdq_ctx lte_crc24a_pclmulqdq, 16) = {
         0x64e4d700,     /**< k1 */
         0x2c8c9d00,     /**< k2 */
@@ -113,6 +117,7 @@ DECLARE_ALIGNED(const uint8_t crc_xmm_shift_tab[48], 16) = {
         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
 };
 
+#endif
 
 void crcTableInit (void)
 {
@@ -128,10 +133,11 @@ void crcTableInit (void)
     crc8Table[c] = (unsigned char) (crcbit (&c, 1, poly8) >> 24);
     crc6Table[c] = (unsigned char) (crcbit (&c, 1, poly6) >> 24);
   } while (++c);
-  if (__builtin_cpu_supports ("pclmul"))
+#ifdef USE_INTEL_CRC
     crc_xmm_be_le_swap128 = _mm_setr_epi32(0x0c0d0e0f, 0x08090a0b,
 					   0x04050607, 0x00010203);
 
+#endif
 }
 
 /*********************************************************
@@ -146,7 +152,7 @@ unsigned int crc24a (unsigned char * inptr,
 {
   int octetlen = bitlen / 8;  /* Change in octets */
 
-  if ( bitlen % 8 || !__builtin_cpu_supports ("pclmul") ) {
+  if ( bitlen % 8 || !USE_INTEL_CRC ) {
   unsigned int      crc = 0;
   int resbit= (bitlen % 8);
     
@@ -158,13 +164,17 @@ unsigned int crc24a (unsigned char * inptr,
   if (resbit > 0)
     crc = (crc << resbit) ^ crc24aTable[((*inptr) >> (8 - resbit)) ^ (crc >> (32 - resbit))];
   return crc;
-  } else {
+  }
+  #if USE_INTEL_CRC
+  else {
   return crc32_calc_pclmulqdq(inptr, octetlen, 0,
                               &lte_crc24a_pclmulqdq);
   }
+  #endif
 
 }
 
+#ifdef USE_INTEL_CRC
 static DECLARE_ALIGNED(struct crc_pclmulqdq_ctx lte_crc24b_pclmulqdq, 16) = {
         0x80140500,     /**< k1 */
         0x42000100,     /**< k2 */
@@ -173,12 +183,13 @@ static DECLARE_ALIGNED(struct crc_pclmulqdq_ctx lte_crc24b_pclmulqdq, 16) = {
         0x80006300,     /**< p */
         0ULL            /**< res */
 };
+#endif
 unsigned int crc24b (unsigned char * inptr,
 	   	     int bitlen)
 {
   int octetlen = bitlen / 8;  /* Change in octets */
   
-  if ( bitlen % 8 || !__builtin_cpu_supports ("pclmul") ) {
+  if ( bitlen % 8 || !USE_INTEL_CRC ) {
   unsigned int crc = 0;
   int resbit = (bitlen % 8);
 
@@ -191,10 +202,13 @@ unsigned int crc24b (unsigned char * inptr,
     crc = (crc << resbit) ^ crc24bTable[((*inptr) >> (8 - resbit)) ^ (crc >> (32 - resbit))];
 
   return crc;
-  } else {
+  }
+#if USE_INTEL_CRC
+  else {
   return crc32_calc_pclmulqdq(inptr, octetlen, 0,
                               &lte_crc24b_pclmulqdq);
   }
+#endif
 }
 
 unsigned int crc24c (unsigned char * inptr,