shithub: libsamplerate

ref: 144174d86da4785c1ba1ee75e09ecc0df49168dc
dir: /cmake/ClipMode.cmake/

macro(CLIP_MODE)

  set(CLIP_MODE_POSITIVE_MESSAGE "Target processor clips on positive float to int conversion")
  set(CLIP_MODE_NEGATIVE_MESSAGE "Target processor clips on negative float to int conversion")

  message(STATUS "Checking processor clipping capabilities...")

  if(CMAKE_CROSSCOMPILING)

    set(CLIP_MSG "disabled")
    set(CPU_CLIPS_POSITIVE FALSE CACHE BOOL ${CLIP_MODE_POSITIVE_MESSAGE})
    set(CPU_CLIPS_NEGATIVE FALSE CACHE BOOL ${CLIP_MODE_NEGATIVE_MESSAGE})

  else()
      include(CheckCSourceRuns)
      include(CMakePushCheckState)
      cmake_push_check_state(RESET)

      if(MATH_LIBRARY)
        list(APPEND CMAKE_REQUIRED_LIBRARIES ${MATH_LIBRARY})
      endif()

      check_c_source_runs(
      "
      #include <math.h>
      int main (void)
      {   double  fval ;
          int k, ival ;

          fval = 1.0 * 0x7FFFFFFF ;
          for (k = 0 ; k < 100 ; k++)
          {   ival = (lrint (fval)) >> 24 ;
              if (ival != 127)
                  return 1 ;

              fval *= 1.2499999 ;
              } ;

              return 0 ;
          }
      "
      CPU_CLIPS_POSITIVE)

      check_c_source_runs(
        "
        #include <math.h>
        int main (void)
        {   double  fval ;
            int k, ival ;

            fval = -8.0 * 0x10000000 ;
            for (k = 0 ; k < 100 ; k++)
            {   ival = (lrint (fval)) >> 24 ;
                if (ival != -128)
                    return 1 ;

                fval *= 1.2499999 ;
                } ;

                return 0 ;
            }
        "
        CPU_CLIPS_NEGATIVE)

      cmake_pop_check_state()

      if(CPU_CLIPS_POSITIVE AND CPU_CLIPS_NEGATIVE)
          set(CLIP_MSG "both")
      elseif(CPU_CLIPS_POSITIVE)
          set(CLIP_MSG "positive")
      elseif(CPU_CLIPS_NEGATIVE)
          set(CLIP_MSG "negative")
      else()
          set(CLIP_MSG "none")
      endif()

  endif()

  message(STATUS "Checking processor clipping capabilities... ${CLIP_MSG}")

endmacro()