From e2b094d5b1e41ec4977fde1dd92aa3339c5244e4 Mon Sep 17 00:00:00 2001
From: Sven Robertz <sven@cs.lth.se>
Date: Tue, 19 Feb 2013 16:07:33 +0100
Subject: [PATCH] simple implementation and test of packing ints
---
lib/c/experimental/pack.c | 73 +++++++++++++++++++++++++++++++++++++++
1 file changed, 73 insertions(+)
create mode 100644 lib/c/experimental/pack.c
diff --git a/lib/c/experimental/pack.c b/lib/c/experimental/pack.c
new file mode 100644
index 0000000..1860964
--- /dev/null
+++ b/lib/c/experimental/pack.c
@@ -0,0 +1,73 @@
+#include <stdio.h>
+
+
+unsigned char do_pack(unsigned char *buf, unsigned long i)
+{
+ printf("do_pack %lu == %lx\n", i, i);
+
+ unsigned long tmp = i;
+ unsigned char res = 0;
+
+ while ( tmp >= 0x80 ) {
+ buf[res] = (tmp & 0x7f) | 0x80;
+ tmp >>= 7;
+ res++;
+ }
+ buf[res] = tmp;
+ return res+1;
+}
+
+unsigned long do_unpack(unsigned char *buf)
+{
+ unsigned long res=0;
+ unsigned char i=0;
+ unsigned char cont=1;
+ do {
+ res |= (buf[i] & 0x7f) << 7*i;
+ cont = buf[i++] & 0x80;
+ } while(cont);
+
+ return res;
+}
+
+void print_packed(unsigned char *buf, unsigned char len)
+{
+ int i;
+
+ for(i=0; i<len;i++) {
+ printf("%2x ", buf[i]);
+ }
+ printf("\n");
+}
+
+int main()
+{
+ unsigned char buf[10];
+ unsigned char len;
+
+ len = do_pack(buf, 10);
+ print_packed(buf, len);
+ printf("... unpacks to %u\n\n", do_unpack(buf));
+
+ len = do_pack(buf, 100);
+ print_packed(buf, len);
+ printf("... unpacks to %u\n\n", do_unpack(buf));
+
+ len = do_pack(buf, 1000);
+ print_packed(buf, len);
+ printf("... unpacks to %u\n\n", do_unpack(buf));
+
+ len = do_pack(buf, 100000);
+ print_packed(buf, len);
+ printf("... unpacks to %u\n\n", do_unpack(buf));
+
+ len = do_pack(buf, 2345678901);
+ print_packed(buf, len);
+ printf("... unpacks to %u\n\n", do_unpack(buf));
+
+ len = do_pack(buf, 0xffffffffffffffff);
+ print_packed(buf, len);
+ printf("... unpacks to %lx\n", do_unpack(buf));
+
+ return 0;
+}
--
GitLab