Support arbitrary lengths when decoding.

[c64tapwav] / decode.c

diff --git a/decode.c b/decode.c
index 7e4c84b182bcea56530cda7bedcb9c3e334e3dd0..e20c8c9d39743f3b0c011fe1d25bc754f81f9152 100644 (file)
--- a/decode.c
+++ b/decode.c
@@ -2,10 +2,12 @@
 #include <math.h>
 #include <unistd.h>
 #include <assert.h>
 #include <math.h>
 #include <unistd.h>
 #include <assert.h>

+#include <vector>

 #include <algorithm>
 
 #define LANCZOS_RADIUS 30
 #include <algorithm>
 
 #define LANCZOS_RADIUS 30

-#define LEN 813440
+#define BUFSIZE 4096
+#define HYSTERESIS_LIMIT 1000

 
 double sinc(double x)
 {
 
 double sinc(double x)
 {


@@ -34,38 +36,36 @@ double weight(double x)
 }
 #endif
 
 }
 #endif
 

-double interpolate(const short *in, double i)
+double interpolate(const std::vector<short> &pcm, double i)

 {
 {

-       int lower = std::max(int(ceil(i - LANCZOS_RADIUS)), 0);
-       int upper = std::min(int(floor(i + LANCZOS_RADIUS)), LEN - 1);
+       int lower = std::max<int>(ceil(i - LANCZOS_RADIUS), 0);
+       int upper = std::min<int>(floor(i + LANCZOS_RADIUS), pcm.size() - 1);

        double sum = 0.0f;
 
        for (int x = lower; x <= upper; ++x) {
        double sum = 0.0f;
 
        for (int x = lower; x <= upper; ++x) {

-               sum += in[x] * weight(i - x);
+               sum += pcm[x] * weight(i - x);

        }
        return sum;
 }
        
        }
        return sum;
 }
        

-short in[LEN];
-

 // between [x,x+1]
 // between [x,x+1]

-double find_zerocrossing(int x)
+double find_zerocrossing(const std::vector<short> &pcm, int x)

 {
 {

-       if (in[x] == 0) {
+       if (pcm[x] == 0) {

                return x;
        }
                return x;
        }

-       if (in[x + 1] == 0) {
+       if (pcm[x + 1] == 0) {

                return x + 1;
        }
 
                return x + 1;
        }
 

-       assert(in[x + 1] > 0);
-       assert(in[x] < 0);
+       assert(pcm[x + 1] > 0);
+       assert(pcm[x] < 0);

 
        double lower = x;
        double upper = x + 1;
        while (upper - lower > 1e-6) {
                double mid = 0.5f * (upper + lower);
 
        double lower = x;
        double upper = x + 1;
        while (upper - lower > 1e-6) {
                double mid = 0.5f * (upper + lower);

-               if (interpolate(in, mid) > 0) {
+               if (interpolate(pcm, mid) > 0) {

                        upper = mid;
                } else {
                        lower = mid;
                        upper = mid;
                } else {
                        lower = mid;


@@ -77,7 +77,15 @@ double find_zerocrossing(int x)
 
 int main(int argc, char **argv)
 {
 
 int main(int argc, char **argv)
 {

-       fread(in, LEN*2, 1, stdin);
+       std::vector<short> pcm;
+
+       while (!feof(stdin)) {
+               short buf[BUFSIZE];
+               ssize_t ret = fread(buf, 2, BUFSIZE, stdin);
+               if (ret >= 0) {
+                       pcm.insert(pcm.end(), buf, buf + ret);
+               }
+       }       

 
 #if 0
        for (int i = 0; i < LEN; ++i) {
 
 #if 0
        for (int i = 0; i < LEN; ++i) {


@@ -92,18 +100,21 @@ int main(int argc, char **argv)
 #endif
        int last_bit = -1;
        double last_upflank = -1;
 #endif
        int last_bit = -1;
        double last_upflank = -1;

-       for (int i = 0; i < LEN; ++i) {
-               int bit = (in[i] > 0) ? 1 : 0;
-               if (bit == 1 && last_bit == 0) {
+       int last_max_level = 0;
+       for (int i = 0; i < pcm.size(); ++i) {
+               int bit = (pcm[i] > 0) ? 1 : 0;
+               if (bit == 1 && last_bit == 0 && last_max_level > HYSTERESIS_LIMIT) {

                        // up-flank!
                        // up-flank!

-                       double t = find_zerocrossing(i - 1) * (123156.0/44100.0);
+                       double t = find_zerocrossing(pcm, i - 1) * (123156.0/44100.0);

                        if (last_upflank > 0) {
 //                             fprintf(stderr, "length: %f (0x%x)\n", t - last_upflank, lrintf(t - last_upflank));
                                int len = lrintf(t - last_upflank);
                                printf("0x%x\n", len);
                        }
                        last_upflank = t;
                        if (last_upflank > 0) {
 //                             fprintf(stderr, "length: %f (0x%x)\n", t - last_upflank, lrintf(t - last_upflank));
                                int len = lrintf(t - last_upflank);
                                printf("0x%x\n", len);
                        }
                        last_upflank = t;

+                       last_max_level = 0;

                }
                }

+               last_max_level = std::max(last_max_level, abs(pcm[i]));

                last_bit = bit;
        }
 }
                last_bit = bit;
        }
 }