# For gcc 4.1.2 on 32-bit Linux systems there have been claims of
# building with sse2 causing faults. The same code and compiler
# version for 64-bit machines seems to run fine. We also have
# not observed the problems with 32-bit OS X machines. In order to provide 
# working code for both 32 bit and 64 bit systems regardless of whether or 
# not SIMD is supported by the hardware, by default the SIMD instructions are
# turned off and must be explicitly enabled by setting ENABLE_SIMD=1
ifdef ENABLE_SIMD
  DISABLE_SIMD=no
endif
ifndef $(DISABLE_SSE2)
  DISABLE_SSE2=no
endif
ifndef $(DISABLE_SSE3)
  DISABLE_SSE3=no
endif

ifeq ($(OS),Linux)
  HAS_SSE =  $(shell if grep -q '^flags.* sse' /proc/cpuinfo; then echo 1; \
                   else echo no; fi)
  HAS_SSE2 = $(shell if grep -q '^flags.* sse2' /proc/cpuinfo; then echo 1; \
                   else echo no; fi)
  HAS_SSE3 = $(shell if grep -q '^flags.*.sse3' /proc/cpuinfo; then echo 1; \
                   else echo no; fi)
  HAS_SSSE3 = $(shell if grep -q '^flags.* ssse3' /proc/cpuinfo; then echo 1; \
                   else echo no; fi)
  HAS_SSE41 = $(shell if grep -q '^flags.* sse4_1' /proc/cpuinfo; then echo 1; \
                   else echo no; fi)
  HAS_SSE42 = $(shell if grep -q '^flags.* sse4_2' /proc/cpuinfo; then echo 1; \
                   else echo no; fi)
  HAS_SSE4A = $(shell if grep -q '^flags.* sse4a' /proc/cpuinfo; then echo 1; \
                   else echo no; fi)
else
# Here someone should put some check for the availability of sse extensions
# on Mac and other non-Linux systems, set some reasonable defaults for now.
  HAS_SSE =  1
  HAS_SSE2 = 1
  HAS_SSE3 = 1
  HAS_SSSE3 = no
  HAS_SSE41 = no
  HAS_SSE42 = no
  HAS_SSE4A = no
endif

ifeq ($(DISABLE_SIMD),no)
  ifneq ($(HAS_SSE),no)
    SIMD_CFLAGS = -DUSE_SIMD -mfpmath=sse -msse
    ifeq ($(DISABLE_SSE2),no)
      ifneq ($(HAS_SSE2),no)
        SIMD_CFLAGS += -DUSE_SSE2 -msse2
        ifeq ($(DISABLE_SSE3),no)
          ifneq ($(HAS_SSE3),no)
            SIMD_CFLAGS += -DUSE_SSE3 -msse3
          else
            SIMD_CFLAGS += -mno-sse3
          endif
        else
          SIMD_CFLAGS += -mno-sse3
        endif
      else
        SIMD_CFLAGS += -mno-sse2
      endif
    else
      SIMD_CFLAGS += -mno-sse2
    endif
  endif
 
  CFLAGS += $(SIMD_CFLAGS)
  CXXFLAGS += $(SIMD_CFLAGS)
endif