#include <stdint.h> // For uintptr_t.
#include <string.h>
#include <libkern/mkext.h>
#define BASE 65521L
#define NMAX 5552 // the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1
#define DO1(buf, i) {s1 += buf[i]; s2 += s1;}
#define DO2(buf, i) DO1(buf,i); DO1(buf,i+1);
#define DO4(buf, i) DO2(buf,i); DO2(buf,i+2);
#define DO8(buf, i) DO4(buf,i); DO4(buf,i+4);
#define DO16(buf) DO8(buf,0); DO8(buf,8);
u_int32_t
mkext_adler32(uint8_t *buf, int32_t len)
{
unsigned long s1 = 1; unsigned long s2 = 0; int k;
while (len > 0) {
k = len < NMAX ? len : NMAX;
len -= k;
while (k >= 16) {
DO16(buf);
buf += 16;
k -= 16;
}
if (k != 0) {
do {
s1 += *buf++;
s2 += s1;
} while (--k);
}
s1 %= BASE;
s2 %= BASE;
}
return (u_int32_t)((s2 << 16) | s1);
}
#define N 4096
#define F 18
#define THRESHOLD 2 * if match_length is greater than this */
#if !KERNEL
#define NIL N
#endif
struct encode_state {
int lchild[N + 1], rchild[N + 257], parent[N + 1];
u_int8_t text_buf[N + F - 1];
int match_position, match_length;
};
int
decompress_lzss(u_int8_t *dst, u_int32_t dstlen, u_int8_t *src, u_int32_t srclen)
{
u_int8_t text_buf[N + F - 1];
u_int8_t *dststart = dst;
u_int8_t *dstend = dst + dstlen;
u_int8_t *srcend = src + srclen;
int i, j, k, r;
u_int8_t c;
unsigned int flags;
dst = dststart;
srcend = src + srclen;
for (i = 0; i < N - F; i++) {
text_buf[i] = ' ';
}
r = N - F;
flags = 0;
for (;;) {
if (((flags >>= 1) & 0x100) == 0) {
if (src < srcend) {
c = *src++;
} else {
break;
}
flags = c | 0xFF00;
}
if (flags & 1) {
if (src < srcend) {
c = *src++;
} else {
break;
}
*dst++ = c;
if (dst >= dstend) {
goto finish;
}
text_buf[r++] = c;
r &= (N - 1);
} else {
if (src < srcend) {
i = *src++;
} else {
break;
}
if (src < srcend) {
j = *src++;
} else {
break;
}
i |= ((j & 0xF0) << 4);
j = (j & 0x0F) + THRESHOLD;
for (k = 0; k <= j; k++) {
c = text_buf[(i + k) & (N - 1)];
*dst++ = c;
if (dst >= dstend) {
goto finish;
}
text_buf[r++] = c;
r &= (N - 1);
}
}
}
finish:
return (int)(dst - dststart);
}
#if !KERNEL
static void
init_state(struct encode_state *sp)
{
int i;
bzero(sp, sizeof(*sp));
for (i = 0; i < N - F; i++) {
sp->text_buf[i] = ' ';
}
for (i = N + 1; i <= N + 256; i++) {
sp->rchild[i] = NIL;
}
for (i = 0; i < N; i++) {
sp->parent[i] = NIL;
}
}
static void
insert_node(struct encode_state *sp, int r)
{
int i, p, cmp;
u_int8_t *key;
cmp = 1;
key = &sp->text_buf[r];
p = N + 1 + key[0];
sp->rchild[r] = sp->lchild[r] = NIL;
sp->match_length = 0;
for (;;) {
if (cmp >= 0) {
if (sp->rchild[p] != NIL) {
p = sp->rchild[p];
} else {
sp->rchild[p] = r;
sp->parent[r] = p;
return;
}
} else {
if (sp->lchild[p] != NIL) {
p = sp->lchild[p];
} else {
sp->lchild[p] = r;
sp->parent[r] = p;
return;
}
}
for (i = 1; i < F; i++) {
if ((cmp = key[i] - sp->text_buf[p + i]) != 0) {
break;
}
}
if (i > sp->match_length) {
sp->match_position = p;
if ((sp->match_length = i) >= F) {
break;
}
}
}
sp->parent[r] = sp->parent[p];
sp->lchild[r] = sp->lchild[p];
sp->rchild[r] = sp->rchild[p];
sp->parent[sp->lchild[p]] = r;
sp->parent[sp->rchild[p]] = r;
if (sp->rchild[sp->parent[p]] == p) {
sp->rchild[sp->parent[p]] = r;
} else {
sp->lchild[sp->parent[p]] = r;
}
sp->parent[p] = NIL;
}
static void
delete_node(struct encode_state *sp, int p)
{
int q;
if (sp->parent[p] == NIL) {
return;
}
if (sp->rchild[p] == NIL) {
q = sp->lchild[p];
} else if (sp->lchild[p] == NIL) {
q = sp->rchild[p];
} else {
q = sp->lchild[p];
if (sp->rchild[q] != NIL) {
do {
q = sp->rchild[q];
} while (sp->rchild[q] != NIL);
sp->rchild[sp->parent[q]] = sp->lchild[q];
sp->parent[sp->lchild[q]] = sp->parent[q];
sp->lchild[q] = sp->lchild[p];
sp->parent[sp->lchild[p]] = q;
}
sp->rchild[q] = sp->rchild[p];
sp->parent[sp->rchild[p]] = q;
}
sp->parent[q] = sp->parent[p];
if (sp->rchild[sp->parent[p]] == p) {
sp->rchild[sp->parent[p]] = q;
} else {
sp->lchild[sp->parent[p]] = q;
}
sp->parent[p] = NIL;
}
#endif