+/* =========================================================================
+ * For the default windowBits of 15 and memLevel of 8, this function returns
+ * a close to exact, as well as small, upper bound on the compressed size.
+ * They are coded as constants here for a reason--if the #define's are
+ * changed, then this function needs to be changed as well. The return
+ * value for 15 and 8 only works for those exact settings.
+ *
+ * For any setting other than those defaults for windowBits and memLevel,
+ * the value returned is a conservative worst case for the maximum expansion
+ * resulting from using fixed blocks instead of stored blocks, which deflate
+ * can emit on compressed data for some combinations of the parameters.
+ *
+ * This function could be more sophisticated to provide closer upper bounds
+ * for every combination of windowBits and memLevel, as well as wrap.
+ * But even the conservative upper bound of about 14% expansion does not
+ * seem onerous for output buffer allocation.
+ */
+uLong ZEXPORT deflateBound(strm, sourceLen)
+ z_streamp strm;
+ uLong sourceLen;
+{
+ deflate_state *s;
+ uLong destLen;
+
+ /* conservative upper bound */
+ destLen = sourceLen +
+ ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 11;
+
+ /* if can't get parameters, return conservative bound */
+ if (strm == Z_NULL || strm->state == Z_NULL)
+ return destLen;
+
+ /* if not default parameters, return conservative bound */
+ s = strm->state;
+ if (s->w_bits != 15 || s->hash_bits != 8 + 7)
+ return destLen;
+
+ /* default settings: return tight bound for that case */
+ return compressBound(sourceLen);
+}
+