AC_CHECK_LIB(m, cosf, [AC_DEFINE([HAVE_COSF],[1],[Define to 1 if your system has `cosf'.])])
AC_CHECK_LIB(m, trunc, [AC_DEFINE([HAVE_TRUNC],[1],[Define to 1 if your system has `trunc'.])])
AC_CHECK_LIB(m, exp10, [AC_DEFINE([HAVE_EXP10],[1],[Define to 1 if your system has 'exp10'.])])
+AC_CHECK_LIB(m, log2, [AC_DEFINE([HAVE_LOG2],[1],[Define to 1 if your system has 'log2'.])])
#AC_FUNC_MKTIME
AH_BOTTOM([
*
*/
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
/* Symbols are offset-binary, with 128 corresponding to an erased (no
* information) symbol
*/
/* Normal function integrated from -Inf to x. Range: 0-1 */
#define normal(x) (0.5 + 0.5*erf((x)/M_SQRT2))
+/* Logarithm base 2 */
+double log2(double); /* declaration seems to be missing from some math.h's */
+#if !defined(HAVE_LOG2)
+#define log2(x) (log(x)*M_LOG2E)
+#endif
+
/* Generate log-likelihood metrics for 8-bit soft quantized channel
* assuming AWGN and BPSK
*/