X-Git-Url: https://git.sesse.net/?p=c64tapwav;a=blobdiff_plain;f=decode.cpp;h=e3ec6775161edf854b2522c99dd9eb724e60af27;hp=798a8729447ab143e51b3fd1bb9f1a11dad572be;hb=9e9da751d8df66b61d930cdf643c65c61ebb4f8a;hpb=35d290f19c02f0e884f4baec704851cfd1b86988

diff --git a/decode.cpp b/decode.cpp
index 798a872..e3ec677 100644
--- a/decode.cpp
+++ b/decode.cpp
@@ -125,10 +125,31 @@ int main(int argc, char **argv)
 	// Find the flanks.
 	int last_bit = -1;
 	double last_upflank = -1;
-	int last_max_level = 0;
 	for (unsigned i = 0; i < pcm.size(); ++i) {
 		int bit = (pcm[i] > 0) ? 1 : 0;
-		if (bit == 1 && last_bit == 0 && last_max_level > HYSTERESIS_LIMIT) {
+		if (bit == 1 && last_bit == 0) {
+			// Check if we ever go up above HYSTERESIS_LIMIT before we dip down again.
+			bool true_pulse = false;
+			unsigned j;
+			int max_level_after = -32768;
+			for (j = i; j < pcm.size(); ++j) {
+				max_level_after = std::max<int>(max_level_after, pcm[j]);
+				if (pcm[j] < 0) break;
+				if (pcm[j] > HYSTERESIS_LIMIT) {
+					true_pulse = true;
+					break;
+				}
+			}
+
+			if (!true_pulse) {
+#if 0
+				fprintf(stderr, "Ignored up-flank at %.6f seconds due to hysteresis (%d < %d).\n",
+					double(i) / SAMPLE_RATE, max_level_after, HYSTERESIS_LIMIT);
+#endif
+				i = j;
+				continue;
+			} 
+
 			// up-flank!
 			double t = find_zerocrossing(pcm, i - 1) * (1.0 / SAMPLE_RATE);
 			if (last_upflank > 0) {
@@ -138,9 +159,7 @@ int main(int argc, char **argv)
 				pulses.push_back(p);
 			}
 			last_upflank = t;
-			last_max_level = 0;
 		}
-		last_max_level = std::max(last_max_level, abs(pcm[i]));
 		last_bit = bit;
 	}
 
@@ -178,9 +197,11 @@ int main(int argc, char **argv)
 			stddev);
 	}
 
+	FILE *fp = fopen("cycles.plot", "w");
 	std::vector<char> tap_data;
 	for (unsigned i = 0; i < pulses.size(); ++i) {
 		double cycles = pulses[i].len * calibration_factor * C64_FREQUENCY;
+		fprintf(fp, "%f %f\n", pulses[i].time, cycles);
 		int len = lrintf(cycles / TAP_RESOLUTION);
 		if (i > SYNC_PULSE_END && (cycles < 100 || cycles > 800)) {
 			fprintf(stderr, "Cycle with upflank at %.6f was detected at %.0f cycles; misdetect?\n",
@@ -196,6 +217,7 @@ int main(int argc, char **argv)
 			tap_data.push_back(overflow_len >> 16);
 		}
 	}
+	fclose(fp);
 
 	tap_header hdr;
 	memcpy(hdr.identifier, "C64-TAPE-RAW", 12);