diff options
Diffstat (limited to 'gr-fec/lib/viterbi/metrics.cc')
| -rw-r--r-- | gr-fec/lib/viterbi/metrics.cc | 15 |
1 files changed, 6 insertions, 9 deletions
diff --git a/gr-fec/lib/viterbi/metrics.cc b/gr-fec/lib/viterbi/metrics.cc index c4c9b01af8..a000558276 100644 --- a/gr-fec/lib/viterbi/metrics.cc +++ b/gr-fec/lib/viterbi/metrics.cc @@ -35,9 +35,6 @@ /* Normal function integrated from -Inf to x. Range: 0-1 */ #define normal(x) (0.5 + 0.5 * erf((x) / GR_M_SQRT2)) -/* Logarithm base 2 */ -#define gr_log2(x) (log(x) * GR_M_LOG2E) - namespace gr { namespace fec { @@ -69,8 +66,8 @@ void gen_met(int mettab[2][256], /* Metric table, [sent sym][rx symbol] */ /* Prob of this value occurring for a 0-bit */ /* P(s|0) */ p0 = normal(((0 - OFFSET + 0.5) / amp + 1) / noise); - metrics[0][0] = gr_log2(2 * p0 / (p1 + p0)) - bias; - metrics[1][0] = gr_log2(2 * p1 / (p1 + p0)) - bias; + metrics[0][0] = ::log2(2 * p0 / (p1 + p0)) - bias; + metrics[1][0] = ::log2(2 * p1 / (p1 + p0)) - bias; for (s = 1; s < 255; s++) { /* P(s|1), prob of receiving s given 1 transmitted */ @@ -84,8 +81,8 @@ void gen_met(int mettab[2][256], /* Metric table, [sent sym][rx symbol] */ #ifdef notdef printf("P(%d|1) = %lg, P(%d|0) = %lg\n", s, p1, s, p0); #endif - metrics[0][s] = gr_log2(2 * p0 / (p1 + p0)) - bias; - metrics[1][s] = gr_log2(2 * p1 / (p1 + p0)) - bias; + metrics[0][s] = ::log2(2 * p0 / (p1 + p0)) - bias; + metrics[1][s] = ::log2(2 * p1 / (p1 + p0)) - bias; } /* 255 is also a special value */ /* P(s|1) */ @@ -93,8 +90,8 @@ void gen_met(int mettab[2][256], /* Metric table, [sent sym][rx symbol] */ /* P(s|0) */ p0 = 1 - normal(((255 - OFFSET - 0.5) / amp + 1) / noise); - metrics[0][255] = gr_log2(2 * p0 / (p1 + p0)) - bias; - metrics[1][255] = gr_log2(2 * p1 / (p1 + p0)) - bias; + metrics[0][255] = ::log2(2 * p0 / (p1 + p0)) - bias; + metrics[1][255] = ::log2(2 * p1 / (p1 + p0)) - bias; #ifdef notdef /* The probability of a raw symbol error is the probability * that a 1-bit would be received as a sample with value |