--- /dev/null
+// "Cleans" tapes by finding the most likely path through a hidden Markov model (HMM),
+// using the Viterbi algorithm. Usually works much worse than e.g. TAPclean;
+// you have been warned :-)
+//
+// Takes in a cycles.plot (from decode) on stdin.
+
+#include <stdio.h>
+#include <string.h>
+#include <math.h>
+#include <assert.h>
+#include <vector>
+#include <map>
+#include <algorithm>
+#include <memory>
+
+#include "tap.h"
+
+#define STATE_BREADTH 75
+
+// From SLC, reportedly from measuring the CIA chip.
+#define SYNC_REFERENCE 378.0
+
+// From http://c64tapes.org/dokuwiki/doku.php?id=loaders:rom_loader.
+#define ROM_SHORT_PULSE_LENGTH (0x30 * 8) // 384
+#define ROM_MEDIUM_PULSE_LENGTH (0x42 * 8) // 528
+#define ROM_LONG_PULSE_LENGTH (0x56 * 8) // 688
+
+// From TAPclean sources.
+#define NOVA_SHORT_PULSE_LENGTH 288
+#define NOVA_LONG_PULSE_LENGTH 688
+
+using namespace std;
+
+enum State { STATE_ROM_SYNC, STATE_ROM_LOADER, STATE_NOVA };
+enum ROMPulseType { ROM_PULSE_TYPE_SHORT = 0, ROM_PULSE_MEDIUM, ROM_PULSE_LONG };
+enum NOVAPulseType { NOVA_PULSE_SHORT = 0, NOVA_PULSE_LONG, NOVA_PULSE_NONE };
+
+static int total_alloc = 0;
+
+struct Node {
+ Node() : prev_node(NULL), refcount(1) { ++total_alloc; }
+ void ref() const { ++refcount; }
+ void unref() const { if (--refcount == 0) { if (prev_node) { prev_node->unref(); } delete this; --total_alloc; } }
+ void set_prev_node(const Node *node) { if (prev_node) { prev_node->unref(); } node->ref(); prev_node = node; }
+ const Node *get_prev_node() const { return prev_node; }
+
+ // Viterbi information.
+ double cost;
+private:
+ const Node* prev_node;
+public:
+ int emit;
+
+ // State information.
+ State state;
+
+ union {
+ // For STATE_ROM_SYNC only.
+ struct {
+ int num_pulses_left;
+ };
+
+ // For STATE_ROM_LOADER.
+ struct {
+ ROMPulseType last_pulse_type;
+ bool first_in_pair; // If the _last_ pulse was first in the pair.
+ };
+
+ // For STATE_NOVA.
+ struct {
+ NOVAPulseType last_nova_pulse_type;
+ };
+ };
+
+private:
+ mutable int refcount;
+ ~Node() {}
+ Node(const Node &);
+};
+
+struct StateLessThanComparator {
+ bool operator() (const Node *a, const Node *b) const
+ {
+ if (a->state != b->state)
+ return (a->state < b->state);
+
+ if (a->state == STATE_ROM_SYNC) {
+ if (a->num_pulses_left != b->num_pulses_left)
+ return (a->num_pulses_left < b->num_pulses_left);
+ }
+
+ if (a->state == STATE_ROM_LOADER) {
+ if (a->last_pulse_type != b->last_pulse_type)
+ return (a->last_pulse_type < b->last_pulse_type);
+ if (a->first_in_pair != b->first_in_pair)
+ return (a->first_in_pair < b->first_in_pair);
+ }
+
+ if (a->state == STATE_NOVA) {
+ if (a->last_nova_pulse_type != b->last_nova_pulse_type)
+ return (a->last_nova_pulse_type < b->last_nova_pulse_type);
+ }
+
+ return false;
+ }
+};
+
+struct StateEqualsComparator {
+ StateLessThanComparator lt;
+
+ bool operator() (const Node *a, const Node *b) const
+ {
+ return !(lt(a, b) || lt(b, a));
+ }
+};
+
+struct CompareByCost {
+ bool operator() (const Node *a, const Node *b) const
+ {
+ return a->cost < b->cost;
+ }
+};
+
+double penalty(double length, double reference, double ratio, double reference_ratio)
+{
+ double ratio_penalty = ((ratio > reference_ratio) ? ratio / reference_ratio : reference_ratio / ratio) - 1.0;
+ double distance_penalty = fabs(length - reference);
+ return ratio_penalty * ratio_penalty + 1e-4 * distance_penalty;
+}
+
+void possibly_add_state(Node *node, vector<Node *> *next_states)
+{
+ next_states->push_back(node);
+}
+
+void extend_state(const Node *prev, double last_length, double length, double ratio, vector<Node *> *next_states)
+{
+ // If this pulse is really long, it means we could transition into another type.
+ if (length > 2000.0) {
+ double cost = 0.0;
+ if (prev->state == STATE_ROM_SYNC) {
+ // We don't really want to jump directly from sync to Novaload sync...
+ cost = min(fabs(0x4f - prev->num_pulses_left), fabs(27136 - prev->num_pulses_left));
+ } else if (prev->state == STATE_ROM_LOADER) {
+ // Jumping in the middle of a bit is bad, too
+ cost = 50.0;
+ }
+
+ // OK, so it could be Nova
+ {
+ Node *n = new Node;
+ n->cost = prev->cost + cost; // + 10.0;
+ n->set_prev_node(prev);
+ n->emit = length;
+
+ n->state = STATE_NOVA;
+ n->last_nova_pulse_type = NOVA_PULSE_NONE;
+ possibly_add_state(n, next_states);
+ }
+ // or maybe the ROM loader
+ {
+ Node *n = new Node;
+ n->cost = prev->cost + cost; // + 10.0;
+ n->set_prev_node(prev);
+ n->emit = length;
+
+ n->state = STATE_ROM_SYNC;
+ n->num_pulses_left = 27136;
+ possibly_add_state(n, next_states);
+ }
+ return; // hack
+ }
+
+ // If in STATE_ROM_SYNC, it's possible that this was another sync pulse.
+ if (prev->state == STATE_ROM_SYNC) {
+ Node *n = new Node;
+ n->cost = prev->cost + penalty(length, SYNC_REFERENCE, ratio, 1.0);
+ n->set_prev_node(prev);
+ n->emit = SYNC_REFERENCE;
+
+ n->state = STATE_ROM_SYNC;
+ n->num_pulses_left = prev->num_pulses_left - 1;
+ possibly_add_state(n, next_states);
+ }
+
+ // If in STATE_ROM_SYNC, maybe we transitioned into ROM_LOADER.
+ // That always starts with a (L,M).
+ if (prev->state == STATE_ROM_SYNC) {
+ Node *n = new Node;
+ n->cost = prev->cost +
+ penalty(length, ROM_LONG_PULSE_LENGTH, ratio, ROM_LONG_PULSE_LENGTH / SYNC_REFERENCE) +
+ 0.1 * fabs(prev->num_pulses_left);
+ n->set_prev_node(prev);
+ n->emit = ROM_LONG_PULSE_LENGTH;
+
+ n->state = STATE_ROM_LOADER;
+ n->last_pulse_type = ROM_PULSE_LONG;
+ n->first_in_pair = true;
+ possibly_add_state(n, next_states);
+ }
+
+ // If in STATE_ROM_SYNC, we could also seemingly transition into Nova data.
+ if (prev->state == STATE_ROM_SYNC) {
+ Node *n = new Node;
+ n->cost = prev->cost +
+ penalty(length, NOVA_SHORT_PULSE_LENGTH, ratio, NOVA_SHORT_PULSE_LENGTH / SYNC_REFERENCE) +
+ 0.1 * fabs(prev->num_pulses_left);
+ n->set_prev_node(prev);
+ n->emit = NOVA_SHORT_PULSE_LENGTH;
+
+ n->state = STATE_NOVA;
+ n->last_nova_pulse_type = NOVA_PULSE_NONE;
+ possibly_add_state(n, next_states);
+ }
+
+ // If in ROM_LOADER, we could have short, medium or long pulses.
+ if (prev->state == STATE_ROM_LOADER) {
+ static const double lengths[] = { ROM_SHORT_PULSE_LENGTH, ROM_MEDIUM_PULSE_LENGTH, ROM_LONG_PULSE_LENGTH };
+ for (int pulse_type = ROM_PULSE_TYPE_SHORT; pulse_type <= ROM_PULSE_LONG; ++pulse_type) {
+
+ // Filter illegal ROM loader pairs.
+ if (prev->last_pulse_type == ROM_PULSE_LONG && pulse_type == ROM_PULSE_LONG) {
+ continue;
+ }
+ if (prev->first_in_pair) {
+ if (prev->last_pulse_type == ROM_PULSE_TYPE_SHORT && pulse_type != ROM_PULSE_MEDIUM) {
+ continue;
+ }
+ if (prev->last_pulse_type == ROM_PULSE_MEDIUM && pulse_type != ROM_PULSE_TYPE_SHORT) {
+ continue;
+ }
+ if (pulse_type == ROM_PULSE_LONG) {
+ continue;
+ }
+ }
+
+ Node *n = new Node;
+ n->cost = prev->cost +
+ penalty(length, lengths[pulse_type], ratio, lengths[pulse_type] / lengths[prev->last_pulse_type]);
+ n->set_prev_node(prev);
+ n->emit = lengths[pulse_type];
+
+ if (prev->first_in_pair && (prev->last_pulse_type == ROM_PULSE_LONG && pulse_type == ROM_PULSE_TYPE_SHORT)) {
+ // (L,S) = end-of-data-marker
+ n->state = STATE_ROM_SYNC;
+ n->num_pulses_left = 0x4f; // http://c64tapes.org/dokuwiki/doku.php?id=loaders:rom_loader
+ } else {
+ n->state = STATE_ROM_LOADER;
+ n->last_pulse_type = ROMPulseType(pulse_type);
+ n->first_in_pair = !prev->first_in_pair;
+ }
+ possibly_add_state(n, next_states);
+ }
+ }
+
+ // If in STATE_NOVA, we only have long and short pulses.
+ if (prev->state == STATE_NOVA) { // hack
+ static const double lengths[] = { NOVA_SHORT_PULSE_LENGTH, NOVA_LONG_PULSE_LENGTH };
+
+ for (int pulse_type = NOVA_PULSE_SHORT; pulse_type <= NOVA_PULSE_LONG; ++pulse_type) {
+
+
+ Node *n = new Node;
+ if (prev->last_nova_pulse_type == NOVA_PULSE_NONE) {
+ n->cost = prev->cost +
+ penalty(length, lengths[pulse_type], length / NOVA_SHORT_PULSE_LENGTH, lengths[pulse_type] / NOVA_SHORT_PULSE_LENGTH);
+ } else {
+ n->cost = prev->cost +
+ penalty(length, lengths[pulse_type], ratio, lengths[pulse_type] / lengths[prev->last_nova_pulse_type]);
+ }
+ n->set_prev_node(prev);
+ n->emit = lengths[pulse_type];
+
+ n->state = STATE_NOVA;
+ n->last_nova_pulse_type = NOVAPulseType(pulse_type);
+ possibly_add_state(n, next_states);
+ }
+ }
+
+ // TODO: Other loader types
+}
+
+int main(int argc, char **argv)
+{
+ Node *start = new Node;
+ start->cost = 0.0;
+ start->emit = -1;
+ start->state = STATE_ROM_SYNC;
+ start->num_pulses_left = 27136;
+
+ vector<Node *> states;
+ states.push_back(start);
+
+ double last_length = SYNC_REFERENCE;
+
+ int pulse_num = 0;
+ int max_total_alloc = 0;
+ for ( ;; ) {
+ double time, length;
+ if (scanf("%lf %lf", &time, &length) != 2) {
+ break;
+ }
+
+ ++pulse_num;
+
+ if (pulse_num % 1000 == 0) {
+ fprintf(stderr, "\rProcessing pulses... %d", pulse_num);
+ }
+
+ max_total_alloc = max(total_alloc, max_total_alloc);
+ if (total_alloc > 20000000) {
+ printf("More than 20M states reached (out of RAM); aborting at pulse %d.\n", pulse_num);
+ break;
+ }
+
+ //if (length > 2000) {
+ // break;
+ //}
+
+ double ratio = length / last_length;
+
+ vector<Node *> next_states;
+ for (unsigned i = 0; i < states.size(); ++i) {
+ extend_state(states[i], last_length, length, ratio, &next_states);
+
+ // We no longer need this state; if it doesn't have any children,
+ // it can go away.
+ states[i]->unref();
+ }
+ states.clear();
+
+ // Remove duplicates, tie-breaking by score.
+ sort(next_states.begin(), next_states.end(), CompareByCost());
+ stable_sort(next_states.begin(), next_states.end(), StateLessThanComparator());
+
+ // unique and move in one step. Do not use std::unique(),
+ // it has very wrong behavior for pointers!
+ for (unsigned i = 0; i < next_states.size(); ++i) {
+ if (i > 0 && StateEqualsComparator()(next_states[i], states.back())) {
+ next_states[i]->unref();
+ } else {
+ states.push_back(next_states[i]);
+ }
+ }
+ assert(!states.empty());
+
+ // Prune unlikely next_states to save time and memory.
+ if (states.size() >= STATE_BREADTH) {
+ sort(states.begin(), states.end(), CompareByCost());
+ for (unsigned i = STATE_BREADTH; i < states.size(); ++i) {
+ states[i]->unref();
+ }
+ states.resize(STATE_BREADTH);
+ }
+ last_length = length;
+ }
+
+ // Find the best final node.
+ const Node *best_node = NULL;
+ for (unsigned i = 0; i < states.size(); ++i) {
+ if (states[i]->state == STATE_ROM_SYNC) {
+ states[i]->cost += 0.1 * fabs(states[i]->num_pulses_left);
+ }
+
+ if (best_node == NULL || states[i]->cost < best_node->cost) {
+ best_node = states[i];
+ }
+ }
+
+ fprintf(stderr, "\rTotal cost is %f. Peak RAM usage %.2f MB, pluss malloc overhead.\n",
+ best_node->cost, sizeof(Node) * max_total_alloc / 1048576.0);
+
+ // Backtrack.
+ vector<const Node *> cleaned;
+ while (best_node != NULL) {
+ cleaned.push_back(best_node);
+ best_node = best_node->get_prev_node();
+ }
+
+ reverse(cleaned.begin(), cleaned.end());
+
+ for (unsigned i = 0; i < cleaned.size(); ++i) {
+ //fprintf(stderr, "%d: state %d emit %d cost %f\n", i, cleaned[i]->state, cleaned[i]->emit, cleaned[i]->cost);
+ if (cleaned[i]->emit <= 0) {
+ continue;
+ }
+ printf("%d\n", cleaned[i]->emit);
+ }
+
+ // output TAP file
+ FILE *fp = fopen("cleaned.tap", "wb");
+ std::vector<char> tap_data;
+ for (unsigned i = 0; i < cleaned.size(); ++i) {
+ if (cleaned[i]->emit <= 0) {
+ continue;
+ }
+ int len = lrintf(cleaned[i]->emit / TAP_RESOLUTION);
+ if (len <= 255) {
+ tap_data.push_back(len);
+ } else {
+ int overflow_len = lrintf(cleaned[i]->emit);
+ tap_data.push_back(0);
+ tap_data.push_back(overflow_len & 0xff);
+ tap_data.push_back((overflow_len >> 8) & 0xff);
+ tap_data.push_back(overflow_len >> 16);
+ }
+ }
+
+ tap_header hdr;
+ memcpy(hdr.identifier, "C64-TAPE-RAW", 12);
+ hdr.version = 1;
+ hdr.reserved[0] = hdr.reserved[1] = hdr.reserved[2] = 0;
+ hdr.data_len = tap_data.size();
+
+ fwrite(&hdr, sizeof(hdr), 1, fp);
+ fwrite(tap_data.data(), tap_data.size(), 1, fp);
+ fclose(fp);
+}
projects / c64tapwav / commitdiff