From d72b557161cb62387d2d6b0311fa664ba09d1655 Mon Sep 17 00:00:00 2001
From: fredrik <fredrik@959494ce-11ee-0310-bf91-de5d638817bd>
Date: Fri, 14 Oct 2005 23:40:00 +0000
Subject: [PATCH] Add trivial HM decoder

git-svn-id: svn+ssh://svn.dolda2000.com/srv/svn/repos/src/doldaconnect@358 959494ce-11ee-0310-bf91-de5d638817bd
---
 daemon/hmdec.c | 99 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 99 insertions(+)
 create mode 100644 daemon/hmdec.c

diff --git a/daemon/hmdec.c b/daemon/hmdec.c
new file mode 100644
index 0000000..bf11c1f
--- /dev/null
+++ b/daemon/hmdec.c
@@ -0,0 +1,99 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+struct node
+{
+    int l, r, c;
+};
+
+struct node tree[512];
+int newnode = 1;
+
+int getbits(int numbits)
+{
+    static int cb = 8, c;
+    int ret;
+    
+    if(numbits < 0)
+    {
+	cb = 8;
+	return(0);
+    }
+    ret = 0;
+    for(; numbits > 0; numbits--)
+    {
+	if(cb >= 8)
+	{
+	    c = getc(stdin);
+	    cb = 0;
+	}
+	ret <<= 1;
+	if(c & (1 << (cb++)))
+	    ret |= 1;
+    }
+    return(ret);
+}
+
+int main(int argc, char **argv) {
+    int i, o;
+    int n;
+    int size, ts, c;
+    int chars[256], lens[256];
+    
+    for(i = 0; i < 512; i++)
+	tree[i].l = tree[i].r = tree[i].c = -1;
+    if((getc(stdin) != 'H') ||
+       (getc(stdin) != 'E') ||
+       (getc(stdin) != '3') ||
+       (getc(stdin) != 13)) {
+	fprintf(stderr, "not a HE3 file\n");
+	exit(1);
+    }
+    getc(stdin);
+    fread(&size, 4, 1, stdin);
+    ts = 0;
+    fread(&ts, 2, 1, stdin);
+    for(i = 0; i < ts; i++) {
+	chars[i] = getc(stdin);
+	lens[i] = getc(stdin);
+    }
+    for(i = 0; i < ts; i++) {
+	n = 0;
+	for(o = 0; o < lens[i]; o++) {
+	    if(getbits(1)) {
+		if(tree[n].r < 0)
+		    n = tree[n].r = newnode++;
+		else
+		    n = tree[n].r;
+	    } else {
+		if(tree[n].l < 0)
+		    n = tree[n].l = newnode++;
+		else
+		    n = tree[n].l;
+	    }
+	}
+	if(tree[n].c >= 0) {
+	    fprintf(stderr, "double-used node: \"%c\"\n", chars[i]);
+	    exit(1);
+	}
+	tree[n].c = chars[i];
+    }
+    getbits(-1);
+    n = 0;
+    for(i = 0; i < size;) {
+	if(getbits(1))
+	    n = tree[n].r;
+	else
+	    n = tree[n].l;
+	if(n < 0) {
+	    fprintf(stderr, "invalid path");
+	    exit(1);
+	}
+	if(tree[n].c >= 0) {
+	    putc(tree[n].c, stdout);
+	    n = 0;
+	    i++;
+	}
+    }
+    return(0);
+}
-- 
2.11.0