jpeg2000: Factor out prec init

Makes debugging a little simpler.

libavcodec/jpeg2000.c

@@ -244,78 +244,15 @@ static void init_band_stepsize(AVCodecContext *avctx,
     band->i_stepsize = band->f_stepsize * (1 << 16);
 }
 
-static int init_band(AVCodecContext *avctx,
+static int init_prec(Jpeg2000Band *band,
                      Jpeg2000ResLevel *reslevel,
                      Jpeg2000Component *comp,
-                     Jpeg2000CodingStyle *codsty,
-                     Jpeg2000QuantStyle *qntsty,
-                     int bandno, int gbandno, int reslevelno,
-                     int cbps, int dx, int dy)
+                     int precno, int bandno, int reslevelno,
+                     int log2_band_prec_width,
+                     int log2_band_prec_height)
 {
-    Jpeg2000Band *band = reslevel->band + bandno;
-    uint8_t log2_band_prec_width, log2_band_prec_height;
-    int declvl = codsty->nreslevels - reslevelno;    // N_L -r see  ISO/IEC 15444-1:2002 B.5
-    int cblkno, precno;
-    int nb_precincts;
-    int i, j;
-
-    init_band_stepsize(avctx, band, codsty, qntsty, bandno, gbandno, reslevelno, cbps);
-
-
-    /* computation of tbx_0, tbx_1, tby_0, tby_1
-     * see ISO/IEC 15444-1:2002 B.5 eq. B-15 and tbl B.1
-     * codeblock width and height is computed for
-     * DCI JPEG 2000 codeblock_width = codeblock_width = 32 = 2 ^ 5 */
-    if (reslevelno == 0) {
-        /* for reslevelno = 0, only one band, x0_b = y0_b = 0 */
-        for (i = 0; i < 2; i++)
-            for (j = 0; j < 2; j++)
-                band->coord[i][j] =
-                    ff_jpeg2000_ceildivpow2(comp->coord_o[i][j] - comp->coord_o[i][0],
-                                            declvl - 1);
-        log2_band_prec_width  = reslevel->log2_prec_width;
-        log2_band_prec_height = reslevel->log2_prec_height;
-        /* see ISO/IEC 15444-1:2002 eq. B-17 and eq. B-15 */
-        band->log2_cblk_width  = FFMIN(codsty->log2_cblk_width,
-                                       reslevel->log2_prec_width);
-        band->log2_cblk_height = FFMIN(codsty->log2_cblk_height,
-                                       reslevel->log2_prec_height);
-    } else {
-        /* 3 bands x0_b = 1 y0_b = 0; x0_b = 0 y0_b = 1; x0_b = y0_b = 1 */
-        /* x0_b and y0_b are computed with ((bandno + 1 >> i) & 1) */
-        for (i = 0; i < 2; i++)
-            for (j = 0; j < 2; j++)
-                /* Formula example for tbx_0 = ceildiv((tcx_0 - 2 ^ (declvl - 1) * x0_b) / declvl) */
-                band->coord[i][j] =
-                    ff_jpeg2000_ceildivpow2(comp->coord_o[i][j] - comp->coord_o[i][0] -
-                                            (((bandno + 1 >> i) & 1) << declvl - 1),
-                                            declvl);
-        /* TODO: Manage case of 3 band offsets here or
-         * in coding/decoding function? */
-
-        /* see ISO/IEC 15444-1:2002 eq. B-17 and eq. B-15 */
-        band->log2_cblk_width  = FFMIN(codsty->log2_cblk_width,
-                                       reslevel->log2_prec_width - 1);
-        band->log2_cblk_height = FFMIN(codsty->log2_cblk_height,
-                                       reslevel->log2_prec_height - 1);
-
-        log2_band_prec_width  = reslevel->log2_prec_width  - 1;
-        log2_band_prec_height = reslevel->log2_prec_height - 1;
-    }
-
-    for (j = 0; j < 2; j++)
-        band->coord[0][j] = ff_jpeg2000_ceildiv(band->coord[0][j], dx);
-    for (j = 0; j < 2; j++)
-        band->coord[1][j] = ff_jpeg2000_ceildiv(band->coord[1][j], dy);
-
-    nb_precincts = reslevel->num_precincts_x * reslevel->num_precincts_y;
-    band->prec = av_mallocz_array(nb_precincts, sizeof(*band->prec));
-    if (!band->prec)
-        return AVERROR(ENOMEM);
-
-    for (precno = 0; precno < nb_precincts; precno++) {
     Jpeg2000Prec *prec = band->prec + precno;
-        int nb_codeblocks;
+    int nb_codeblocks, cblkno;
 
     /* TODO: Explain formula for JPEG200 DCINEMA. */
     /* TODO: Verify with previous count of codeblocks per band */
@@ -408,6 +345,85 @@ static int init_band(AVCodecContext *avctx,
         cblk->lengthinc = 0;
         cblk->npasses   = 0;
     }
+
+    return 0;
+}
+
+static int init_band(AVCodecContext *avctx,
+                     Jpeg2000ResLevel *reslevel,
+                     Jpeg2000Component *comp,
+                     Jpeg2000CodingStyle *codsty,
+                     Jpeg2000QuantStyle *qntsty,
+                     int bandno, int gbandno, int reslevelno,
+                     int cbps, int dx, int dy)
+{
+    Jpeg2000Band *band = reslevel->band + bandno;
+    uint8_t log2_band_prec_width, log2_band_prec_height;
+    int declvl = codsty->nreslevels - reslevelno;    // N_L -r see  ISO/IEC 15444-1:2002 B.5
+    int precno;
+    int nb_precincts;
+    int i, j, ret;
+
+    init_band_stepsize(avctx, band, codsty, qntsty, bandno, gbandno, reslevelno, cbps);
+
+
+    /* computation of tbx_0, tbx_1, tby_0, tby_1
+     * see ISO/IEC 15444-1:2002 B.5 eq. B-15 and tbl B.1
+     * codeblock width and height is computed for
+     * DCI JPEG 2000 codeblock_width = codeblock_width = 32 = 2 ^ 5 */
+    if (reslevelno == 0) {
+        /* for reslevelno = 0, only one band, x0_b = y0_b = 0 */
+        for (i = 0; i < 2; i++)
+            for (j = 0; j < 2; j++)
+                band->coord[i][j] =
+                    ff_jpeg2000_ceildivpow2(comp->coord_o[i][j] - comp->coord_o[i][0],
+                                            declvl - 1);
+        log2_band_prec_width  = reslevel->log2_prec_width;
+        log2_band_prec_height = reslevel->log2_prec_height;
+        /* see ISO/IEC 15444-1:2002 eq. B-17 and eq. B-15 */
+        band->log2_cblk_width  = FFMIN(codsty->log2_cblk_width,
+                                       reslevel->log2_prec_width);
+        band->log2_cblk_height = FFMIN(codsty->log2_cblk_height,
+                                       reslevel->log2_prec_height);
+    } else {
+        /* 3 bands x0_b = 1 y0_b = 0; x0_b = 0 y0_b = 1; x0_b = y0_b = 1 */
+        /* x0_b and y0_b are computed with ((bandno + 1 >> i) & 1) */
+        for (i = 0; i < 2; i++)
+            for (j = 0; j < 2; j++)
+                /* Formula example for tbx_0 = ceildiv((tcx_0 - 2 ^ (declvl - 1) * x0_b) / declvl) */
+                band->coord[i][j] =
+                    ff_jpeg2000_ceildivpow2(comp->coord_o[i][j] - comp->coord_o[i][0] -
+                                            (((bandno + 1 >> i) & 1) << declvl - 1),
+                                            declvl);
+        /* TODO: Manage case of 3 band offsets here or
+         * in coding/decoding function? */
+
+        /* see ISO/IEC 15444-1:2002 eq. B-17 and eq. B-15 */
+        band->log2_cblk_width  = FFMIN(codsty->log2_cblk_width,
+                                       reslevel->log2_prec_width - 1);
+        band->log2_cblk_height = FFMIN(codsty->log2_cblk_height,
+                                       reslevel->log2_prec_height - 1);
+
+        log2_band_prec_width  = reslevel->log2_prec_width  - 1;
+        log2_band_prec_height = reslevel->log2_prec_height - 1;
+    }
+
+    for (j = 0; j < 2; j++)
+        band->coord[0][j] = ff_jpeg2000_ceildiv(band->coord[0][j], dx);
+    for (j = 0; j < 2; j++)
+        band->coord[1][j] = ff_jpeg2000_ceildiv(band->coord[1][j], dy);
+
+    nb_precincts = reslevel->num_precincts_x * reslevel->num_precincts_y;
+    band->prec = av_mallocz_array(nb_precincts, sizeof(*band->prec));
+    if (!band->prec)
+        return AVERROR(ENOMEM);
+
+    for (precno = 0; precno < nb_precincts; precno++) {
+        ret = init_prec(band, reslevel, comp,
+                        precno, bandno, reslevelno,
+                        log2_band_prec_width, log2_band_prec_height);
+        if (ret < 0)
+            return ret;
     }
 
     return 0;