opj_tcd_dc_level_shift_decode(): optimize lossy case

diff --git a/src/lib/openjp2/opj_intmath.h b/src/lib/openjp2/opj_intmath.h
index d7d85e52ccf004e0674211549ccc94e60b4283f8..ad13597661319d8eda186143e3fb7b2c0019bdd3 100644 (file)
--- a/src/lib/openjp2/opj_intmath.h
+++ b/src/lib/openjp2/opj_intmath.h
@@ -124,6 +124,28 @@ static INLINE OPJ_INT32 opj_int_clamp(OPJ_INT32 a, OPJ_INT32 min,
     }
     return a;
 }
+
+/**
+Clamp an integer inside an interval
+@return
+<ul>
+<li>Returns a if (min < a < max)
+<li>Returns max if (a > max)
+<li>Returns min if (a < min)
+</ul>
+*/
+static INLINE OPJ_INT64 opj_int64_clamp(OPJ_INT64 a, OPJ_INT64 min,
+                                        OPJ_INT64 max)
+{
+    if (a < min) {
+        return min;
+    }
+    if (a > max) {
+        return max;
+    }
+    return a;
+}
+
 /**
 @return Get absolute value of integer
 */

diff --git a/src/lib/openjp2/tcd.c b/src/lib/openjp2/tcd.c
index 3bcab981036fe348881fe51a320e8fb2bca6ec84..26c9f2a48f170eae1a1541df59d685e899096919 100644 (file)
--- a/src/lib/openjp2/tcd.c
+++ b/src/lib/openjp2/tcd.c
@@ -2112,6 +2112,7 @@ static OPJ_BOOL opj_tcd_dc_level_shift_decode(opj_tcd_t *p_tcd)
         if (l_tccp->qmfbid == 1) {
             for (j = 0; j < l_height; ++j) {
                 for (i = 0; i < l_width; ++i) {
+                    /* TODO: do addition on int64 ? */
                     *l_current_ptr = opj_int_clamp(*l_current_ptr + l_tccp->m_dc_level_shift, l_min,
                                                    l_max);
                     ++l_current_ptr;
@@ -2122,13 +2123,14 @@ static OPJ_BOOL opj_tcd_dc_level_shift_decode(opj_tcd_t *p_tcd)
             for (j = 0; j < l_height; ++j) {
                 for (i = 0; i < l_width; ++i) {
                     OPJ_FLOAT32 l_value = *((OPJ_FLOAT32 *) l_current_ptr);
-                    OPJ_INT32 l_value_int = (OPJ_INT32)opj_lrintf(l_value);
-                    if (l_value > INT_MAX ||
-                            (l_value_int > 0 && l_tccp->m_dc_level_shift > 0 &&
-                             l_value_int > INT_MAX - l_tccp->m_dc_level_shift)) {
+                    if (l_value > INT_MAX) {
                         *l_current_ptr = l_max;
+                    } else if (l_value < INT_MIN) {
+                        *l_current_ptr = l_min;
                     } else {
-                        *l_current_ptr = opj_int_clamp(
+                        /* Do addition on int64 to avoid overflows */
+                        OPJ_INT64 l_value_int = (OPJ_INT64)opj_lrintf(l_value);
+                        *l_current_ptr = (OPJ_INT32)opj_int64_clamp(
                                              l_value_int + l_tccp->m_dc_level_shift, l_min, l_max);
                     }
                     ++l_current_ptr;