Update audio code to use size_t more correctly, webrtc/common_audio/ portion.

webrtc/common_audio/fft4g.c

 /*
  * http://www.kurims.kyoto-u.ac.jp/~ooura/fft.html
  * Copyright Takuya OOURA, 1996-2001
  *
  * You may use, copy, modify and distribute this code for any purpose (include
  * commercial use) and without fee. Please refer to this package when you modify
  * this code.
  *
  * Changes:
  * Trivial type modifications by the WebRTC authors.
@@ skipping 268 matching lines @@
                 a[j] *= 2.0 / n;
             }
         .
 
 
 Appendix :
     The cos/sin table is recalculated when the larger table required.
     w[] and ip[] are compatible with all routines.
 */
 
-static void makewt(int nw, int *ip, float *w);
-static void makect(int nc, int *ip, float *c);
-static void bitrv2(int n, int *ip, float *a);
+#include <stddef.h>
+
+static void makewt(size_t nw, size_t *ip, float *w);

[Andrew MacDonald, 2015/07/24 19:01:55]

It's not totally clear to me that this "work area for bit reversal" should be a
size_t. Would you mind explaining the rationale?

[Peter Kasting, 2015/07/27 23:23:39]

The type of *ip has to match the type of |n| in the externally-visible rdft()
declaration (or, in these helpers, |nw|, |nc|, |n|, etc.).  This is because
these are all passed around interchangeably, stored in each other, etc.

AFAICT from a quick read, |ip| basically holds offsets into the other tables, so
semantically its meaning is array-of-size_t.

(Also I updated a few comments here to match my changes.)

[Andrew MacDonald, 2015/07/28 07:20:05]

OK thanks for the explanation.

+static void makect(size_t nc, size_t *ip, float *c);
+static void bitrv2(size_t n, size_t *ip, float *a);
 #if 0  // Not used.
 static void bitrv2conj(int n, int *ip, float *a);
 #endif
-static void cftfsub(int n, float *a, float *w);
-static void cftbsub(int n, float *a, float *w);
-static void cft1st(int n, float *a, float *w);
-static void cftmdl(int n, int l, float *a, float *w);
-static void rftfsub(int n, float *a, int nc, float *c);
-static void rftbsub(int n, float *a, int nc, float *c);
+static void cftfsub(size_t n, float *a, float *w);
+static void cftbsub(size_t n, float *a, float *w);
+static void cft1st(size_t n, float *a, float *w);
+static void cftmdl(size_t n, size_t l, float *a, float *w);
+static void rftfsub(size_t n, float *a, size_t nc, float *c);
+static void rftbsub(size_t n, float *a, size_t nc, float *c);
 #if 0  // Not used.
 static void dctsub(int n, float *a, int nc, float *c)
 static void dstsub(int n, float *a, int nc, float *c)
 #endif
 
 
 #if 0  // Not used.
 void WebRtc_cdft(int n, int isgn, float *a, int *ip, float *w)
 {
     if (n > (ip[0] << 2)) {
         makewt(n >> 2, ip, w);
     }
     if (n > 4) {
         if (isgn >= 0) {
             bitrv2(n, ip + 2, a);
             cftfsub(n, a, w);
         } else {
             bitrv2conj(n, ip + 2, a);
             cftbsub(n, a, w);
         }
     } else if (n == 4) {
         cftfsub(n, a, w);
     }
 }
 #endif
 
 
-void WebRtc_rdft(int n, int isgn, float *a, int *ip, float *w)
+void WebRtc_rdft(size_t n, int isgn, float *a, size_t *ip, float *w)
 {
-    int nw, nc;
+    size_t nw, nc;
     float xi;
 
     nw = ip[0];
     if (n > (nw << 2)) {
         nw = n >> 2;
         makewt(nw, ip, w);
     }
     nc = ip[1];
     if (n > (nc << 2)) {
         nc = n >> 2;
@@ skipping 295 matching lines @@
     a[0] = 0;
 }
 #endif  // Not used.
 
 
 /* -------- initializing routines -------- */
 
 
 #include <math.h>
 
-static void makewt(int nw, int *ip, float *w)
+static void makewt(size_t nw, size_t *ip, float *w)
 {
-    int j, nwh;
+    size_t j, nwh;
     float delta, x, y;
 
     ip[0] = nw;
     ip[1] = 1;
     if (nw > 2) {
         nwh = nw >> 1;
         delta = atanf(1.0f) / nwh;
         w[0] = 1;
         w[1] = 0;
         w[nwh] = (float)cos(delta * nwh);
         w[nwh + 1] = w[nwh];
         if (nwh > 2) {
             for (j = 2; j < nwh; j += 2) {
                 x = (float)cos(delta * j);
                 y = (float)sin(delta * j);
                 w[j] = x;
                 w[j + 1] = y;
                 w[nw - j] = y;
                 w[nw - j + 1] = x;
             }
             bitrv2(nw, ip + 2, w);
         }
     }
 }
 
 
-static void makect(int nc, int *ip, float *c)
+static void makect(size_t nc, size_t *ip, float *c)
 {
-    int j, nch;
+    size_t j, nch;
     float delta;
 
     ip[1] = nc;
     if (nc > 1) {
         nch = nc >> 1;
         delta = atanf(1.0f) / nch;
         c[0] = (float)cos(delta * nch);
         c[nch] = 0.5f * c[0];
         for (j = 1; j < nch; j++) {
             c[j] = 0.5f * (float)cos(delta * j);
             c[nc - j] = 0.5f * (float)sin(delta * j);
         }
     }
 }
 
 
 /* -------- child routines -------- */
 
 
-static void bitrv2(int n, int *ip, float *a)
+static void bitrv2(size_t n, size_t *ip, float *a)
 {
-    int j, j1, k, k1, l, m, m2;
+    size_t j, j1, k, k1, l, m, m2;
     float xr, xi, yr, yi;
 
     ip[0] = 0;
     l = n;
     m = 1;
     while ((m << 3) < l) {
         l >>= 1;
         for (j = 0; j < m; j++) {
             ip[m + j] = ip[j] + l;
         }
@@ skipping 186 matching lines @@
                 a[k1 + 1] = xi;
             }
             k1 = 2 * k + ip[k];
             a[k1 + 1] = -a[k1 + 1];
             a[k1 + m2 + 1] = -a[k1 + m2 + 1];
         }
     }
 }
 #endif
 
-static void cftfsub(int n, float *a, float *w)
+static void cftfsub(size_t n, float *a, float *w)
 {
-    int j, j1, j2, j3, l;
+    size_t j, j1, j2, j3, l;
     float x0r, x0i, x1r, x1i, x2r, x2i, x3r, x3i;
 
     l = 2;
     if (n > 8) {
         cft1st(n, a, w);
         l = 8;
         while ((l << 2) < n) {
             cftmdl(n, l, a, w);
             l <<= 2;
         }
@@ skipping 27 matching lines @@
             x0i = a[j + 1] - a[j1 + 1];
             a[j] += a[j1];
             a[j + 1] += a[j1 + 1];
             a[j1] = x0r;
             a[j1 + 1] = x0i;
         }
     }
 }
 
 
-static void cftbsub(int n, float *a, float *w)
+static void cftbsub(size_t n, float *a, float *w)
 {
-    int j, j1, j2, j3, l;
+    size_t j, j1, j2, j3, l;
     float x0r, x0i, x1r, x1i, x2r, x2i, x3r, x3i;
 
     l = 2;
     if (n > 8) {
         cft1st(n, a, w);
         l = 8;
         while ((l << 2) < n) {
             cftmdl(n, l, a, w);
             l <<= 2;
         }
@@ skipping 27 matching lines @@
             x0i = -a[j + 1] + a[j1 + 1];
             a[j] += a[j1];
             a[j + 1] = -a[j + 1] - a[j1 + 1];
             a[j1] = x0r;
             a[j1 + 1] = x0i;
         }
     }
 }
 
 
-static void cft1st(int n, float *a, float *w)
+static void cft1st(size_t n, float *a, float *w)
 {
-    int j, k1, k2;
+    size_t j, k1, k2;
     float wk1r, wk1i, wk2r, wk2i, wk3r, wk3i;
     float x0r, x0i, x1r, x1i, x2r, x2i, x3r, x3i;
 
     x0r = a[0] + a[2];
     x0i = a[1] + a[3];
     x1r = a[0] - a[2];
     x1i = a[1] - a[3];
     x2r = a[4] + a[6];
     x2i = a[5] + a[7];
     x3r = a[4] - a[6];
@@ skipping 82 matching lines @@
         a[j + 10] = wk1r * x0r - wk1i * x0i;
         a[j + 11] = wk1r * x0i + wk1i * x0r;
         x0r = x1r + x3i;
         x0i = x1i - x3r;
         a[j + 14] = wk3r * x0r - wk3i * x0i;
         a[j + 15] = wk3r * x0i + wk3i * x0r;
     }
 }
 
 
-static void cftmdl(int n, int l, float *a, float *w)
+static void cftmdl(size_t n, size_t l, float *a, float *w)
 {
-    int j, j1, j2, j3, k, k1, k2, m, m2;
+    size_t j, j1, j2, j3, k, k1, k2, m, m2;
     float wk1r, wk1i, wk2r, wk2i, wk3r, wk3i;
     float x0r, x0i, x1r, x1i, x2r, x2i, x3r, x3i;
 
     m = l << 2;
     for (j = 0; j < l; j += 2) {
         j1 = j + l;
         j2 = j1 + l;
         j3 = j2 + l;
         x0r = a[j] + a[j1];
         x0i = a[j + 1] + a[j1 + 1];
@@ skipping 104 matching lines @@
             a[j1 + 1] = wk1r * x0i + wk1i * x0r;
             x0r = x1r + x3i;
             x0i = x1i - x3r;
             a[j3] = wk3r * x0r - wk3i * x0i;
             a[j3 + 1] = wk3r * x0i + wk3i * x0r;
         }
     }
 }
 
 
-static void rftfsub(int n, float *a, int nc, float *c)
+static void rftfsub(size_t n, float *a, size_t nc, float *c)
 {
-    int j, k, kk, ks, m;
+    size_t j, k, kk, ks, m;
     float wkr, wki, xr, xi, yr, yi;
 
     m = n >> 1;
     ks = 2 * nc / m;
     kk = 0;
     for (j = 2; j < m; j += 2) {
         k = n - j;
         kk += ks;
         wkr = 0.5f - c[nc - kk];
         wki = c[kk];
         xr = a[j] - a[k];
         xi = a[j + 1] + a[k + 1];
         yr = wkr * xr - wki * xi;
         yi = wkr * xi + wki * xr;
         a[j] -= yr;
         a[j + 1] -= yi;
         a[k] += yr;
         a[k + 1] -= yi;
     }
 }
 
 
-static void rftbsub(int n, float *a, int nc, float *c)
+static void rftbsub(size_t n, float *a, size_t nc, float *c)
 {
-    int j, k, kk, ks, m;
+    size_t j, k, kk, ks, m;
     float wkr, wki, xr, xi, yr, yi;
 
     a[1] = -a[1];
     m = n >> 1;
     ks = 2 * nc / m;
     kk = 0;
     for (j = 2; j < m; j += 2) {
         k = n - j;
         kk += ks;
         wkr = 0.5f - c[nc - kk];
@@ skipping 45 matching lines @@
         kk += ks;
         wkr = c[kk] - c[nc - kk];
         wki = c[kk] + c[nc - kk];
         xr = wki * a[k] - wkr * a[j];
         a[k] = wkr * a[k] + wki * a[j];
         a[j] = xr;
     }
     a[m] *= c[0];
 }
 #endif  // Not used.