jepler/uzlib
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

Provide option to have predefined static extra bits tables.

Browse source 
Having a neat algo to create them at runtime is neat, but on embedded
systems, RAM is precious, ROM is less so.
This commit is contained in:
Paul Sokolovsky 2014-08-20 04:28:50 +03:00
parent 29957f12a0
commit 81ae6225de
1 changed files with 36 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

36
src/tinflate.c
View file

@ -58,6 +58,8 @@ typedef struct {
* -- uninitialized global data (static structures) -- *
* --------------------------------------------------- */
#ifdef RUNTIME_BITS_TABLES
/* extra bits and base tables for length codes */
unsigned char length_bits[30];
unsigned short length_base[30];
@ -66,6 +68,36 @@ unsigned short length_base[30];
unsigned char dist_bits[30];
unsigned short dist_base[30];
#else
const unsigned char length_bits[30] = {
0, 0, 0, 0, 0, 0, 0, 0,
1, 1, 1, 1, 2, 2, 2, 2,
3, 3, 3, 3, 4, 4, 4, 4,
5, 5, 5, 5
};
const unsigned short length_base[30] = {
3, 4, 5, 6, 7, 8, 9, 10,
11, 13, 15, 17, 19, 23, 27, 31,
35, 43, 51, 59, 67, 83, 99, 115,
131, 163, 195, 227, 258
};
const unsigned char dist_bits[30] = {
0, 0, 0, 0, 1, 1, 2, 2,
3, 3, 4, 4, 5, 5, 6, 6,
7, 7, 8, 8, 9, 9, 10, 10,
11, 11, 12, 12, 13, 13
};
const unsigned short dist_base[30] = {
1, 2, 3, 4, 5, 7, 9, 13,
17, 25, 33, 49, 65, 97, 129, 193,
257, 385, 513, 769, 1025, 1537, 2049, 3073,
4097, 6145, 8193, 12289, 16385, 24577
};
#endif
/* special ordering of code length codes */
const unsigned char clcidx[] = {
16, 17, 18, 0, 8, 7, 9, 6,
@ -77,6 +109,7 @@ const unsigned char clcidx[] = {
* -- utility functions -- *
* ----------------------- */
#ifdef RUNTIME_BITS_TABLES
/* build extra bits and base tables */
static void tinf_build_bits_base(unsigned char *bits, unsigned short *base, int delta, int first)
{
@ -93,6 +126,7 @@ static void tinf_build_bits_base(unsigned char *bits, unsigned short *base, int
sum += 1 << bits[i];
}
}
#endif
/* build the fixed huffman trees */
static void tinf_build_fixed_trees(TINF_TREE *lt, TINF_TREE *dt)
@ -390,6 +424,7 @@ static int tinf_inflate_dynamic_block(TINF_DATA *d)
/* initialize global (static) data */
void tinf_init()
{
#ifdef RUNTIME_BITS_TABLES
/* build extra bits and base tables */
tinf_build_bits_base(length_bits, length_base, 4, 3);
tinf_build_bits_base(dist_bits, dist_base, 2, 1);
@ -397,6 +432,7 @@ void tinf_init()
/* fix a special case */
length_bits[28] = 0;
length_base[28] = 258;
#endif
}
/* inflate stream from source to dest */