Adding lzss.c as provided in the public domain by Haruhiko Okumura

Author: aentinger

libraries/SSU/extras/SSUBoot/lzss.c

@@ -0,0 +1,180 @@
+/* LZSS encoder-decoder (Haruhiko Okumura; public domain) */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#define EI 11  /* typically 10..13 */
+#define EJ  4  /* typically 4..5 */
+#define P   1  /* If match length <= P then output one character */
+#define N (1 << EI)  /* buffer size */
+#define F ((1 << EJ) + 1)  /* lookahead buffer size */
+
+int bit_buffer = 0, bit_mask = 128;
+unsigned long codecount = 0, textcount = 0;
+unsigned char buffer[N * 2];
+FILE *infile, *outfile;
+
+void error(void)
+{
+    printf("Output error\n");  exit(1);
+}
+
+void putbit1(void)
+{
+    bit_buffer |= bit_mask;
+    if ((bit_mask >>= 1) == 0) {
+        if (fputc(bit_buffer, outfile) == EOF) error();
+        bit_buffer = 0;  bit_mask = 128;  codecount++;
+    }
+}
+
+void putbit0(void)
+{
+    if ((bit_mask >>= 1) == 0) {
+        if (fputc(bit_buffer, outfile) == EOF) error();
+        bit_buffer = 0;  bit_mask = 128;  codecount++;
+    }
+}
+
+void flush_bit_buffer(void)
+{
+    if (bit_mask != 128) {
+        if (fputc(bit_buffer, outfile) == EOF) error();
+        codecount++;
+    }
+}
+
+void output1(int c)
+{
+    int mask;
+    
+    putbit1();
+    mask = 256;
+    while (mask >>= 1) {
+        if (c & mask) putbit1();
+        else putbit0();
+    }
+}
+
+void output2(int x, int y)
+{
+    int mask;
+    
+    putbit0();
+    mask = N;
+    while (mask >>= 1) {
+        if (x & mask) putbit1();
+        else putbit0();
+    }
+    mask = (1 << EJ);
+    while (mask >>= 1) {
+        if (y & mask) putbit1();
+        else putbit0();
+    }
+}
+
+void encode(void)
+{
+    int i, j, f1, x, y, r, s, bufferend, c;
+    
+    for (i = 0; i < N - F; i++) buffer[i] = ' ';
+    for (i = N - F; i < N * 2; i++) {
+        if ((c = fgetc(infile)) == EOF) break;
+        buffer[i] = c;  textcount++;
+    }
+    bufferend = i;  r = N - F;  s = 0;
+    while (r < bufferend) {
+        f1 = (F <= bufferend - r) ? F : bufferend - r;
+        x = 0;  y = 1;  c = buffer[r];
+        for (i = r - 1; i >= s; i--)
+            if (buffer[i] == c) {
+                for (j = 1; j < f1; j++)
+                    if (buffer[i + j] != buffer[r + j]) break;
+                if (j > y) {
+                    x = i;  y = j;
+                }
+            }
+        if (y <= P) {  y = 1;  output1(c);  }
+        else output2(x & (N - 1), y - 2);
+        r += y;  s += y;
+        if (r >= N * 2 - F) {
+            for (i = 0; i < N; i++) buffer[i] = buffer[i + N];
+            bufferend -= N;  r -= N;  s -= N;
+            while (bufferend < N * 2) {
+                if ((c = fgetc(infile)) == EOF) break;
+                buffer[bufferend++] = c;  textcount++;
+            }
+        }
+    }
+    flush_bit_buffer();
+    printf("text:  %ld bytes\n", textcount);
+    printf("code:  %ld bytes (%ld%%)\n",
+        codecount, (codecount * 100) / textcount);
+}
+
+int getbit(int n) /* get n bits */
+{
+    int i, x;
+    static int buf, mask = 0;
+    
+    x = 0;
+    for (i = 0; i < n; i++) {
+        if (mask == 0) {
+            if ((buf = fgetc(infile)) == EOF) return EOF;
+            mask = 128;
+        }
+        x <<= 1;
+        if (buf & mask) x++;
+        mask >>= 1;
+    }
+    return x;
+}
+
+void decode(void)
+{
+    int i, j, k, r, c;
+    
+    for (i = 0; i < N - F; i++) buffer[i] = ' ';
+    r = N - F;
+    while ((c = getbit(1)) != EOF) {
+        if (c) {
+            if ((c = getbit(8)) == EOF) break;
+            fputc(c, outfile);
+            buffer[r++] = c;  r &= (N - 1);
+        } else {
+            if ((i = getbit(EI)) == EOF) break;
+            if ((j = getbit(EJ)) == EOF) break;
+            for (k = 0; k <= j + 1; k++) {
+                c = buffer[(i + k) & (N - 1)];
+                fputc(c, outfile);
+                buffer[r++] = c;  r &= (N - 1);
+            }
+        }
+    }
+}
+
+int main(int argc, char *argv[])
+{
+    int enc;
+    char *s;
+    
+    if (argc != 4) {
+        printf("Usage: lzss e/d infile outfile\n\te = encode\td = decode\n");
+        return 1;
+    }
+    s = argv[1];
+    if (s[1] == 0 && (*s == 'd' || *s == 'D' || *s == 'e' || *s == 'E'))
+        enc = (*s == 'e' || *s == 'E');
+    else {
+        printf("? %s\n", s);  return 1;
+    }
+    if ((infile  = fopen(argv[2], "rb")) == NULL) {
+        printf("? %s\n", argv[2]);  return 1;
+    }
+    if ((outfile = fopen(argv[3], "wb")) == NULL) {
+        printf("? %s\n", argv[3]);  return 1;
+    }
+    if (enc) encode();  else decode();
+    fclose(infile);  fclose(outfile);
+    return 0;
+}