diff options
Diffstat (limited to 'deflate.c')
| -rw-r--r-- | deflate.c | 60 |
1 files changed, 46 insertions, 14 deletions
@@ -52,7 +52,7 @@ #include "deflate.h" const char deflate_copyright[] = - " deflate 1.2.3 Copyright 1995-2005 Jean-loup Gailly "; + " deflate 1.2.3.1 Copyright 1995-2005 Jean-loup Gailly "; /* If you use the zlib library in a product, an acknowledgment is welcome in the documentation of your product. If for some reason you cannot @@ -481,33 +481,65 @@ int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain) * 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. + * This function could be more sophisticated to provide closer upper bounds for + * every combination of windowBits and memLevel. 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; + uLong complen, wraplen; + Bytef *str; - /* conservative upper bound */ - destLen = sourceLen + - ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 11; + /* conservative upper bound for compressed data */ + complen = sourceLen + + ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5; - /* if can't get parameters, return conservative bound */ + /* if can't get parameters, return conservative bound plus zlib wrapper */ if (strm == Z_NULL || strm->state == Z_NULL) - return destLen; + return complen + 6; - /* if not default parameters, return conservative bound */ + /* compute wrapper length */ s = strm->state; + switch (s->wrap) { + case 0: /* raw deflate */ + wraplen = 0; + break; + case 1: /* zlib wrapper */ + wraplen = 6 + (s->strstart ? 4 : 0); + break; + case 2: /* gzip wrapper */ + wraplen = 18; + if (s->gzhead != NULL) { /* user-supplied gzip header */ + if (s->gzhead->extra != NULL) + wraplen += 2 + s->gzhead->extra_len; + str = s->gzhead->name; + if (str != NULL) + do { + wraplen++; + } while (*str++); + str = s->gzhead->comment; + if (str != NULL) + do { + wraplen++; + } while (*str++); + if (s->gzhead->hcrc) + wraplen += 2; + } + break; + default: /* for compiler happiness */ + wraplen = 6; + } + + /* if not default parameters, return conservative bound */ if (s->w_bits != 15 || s->hash_bits != 8 + 7) - return destLen; + return complen + wraplen; /* default settings: return tight bound for that case */ - return compressBound(sourceLen); + return compressBound(sourceLen) - 6 + wraplen; } /* ========================================================================= |