X-Git-Url: https://git.draconx.ca/gitweb/upkg.git/blobdiff_plain/959d4dd5bc102359f414a7feb718d56bf1b012e6..5fe7c42921be9f911805b4006f59a0910c9404d0:/src/pack.c

diff --git a/src/pack.c b/src/pack.c
index b87ac34..9f4998f 100644
--- a/src/pack.c
+++ b/src/pack.c
@@ -22,7 +22,7 @@
 
 #include "pack.h"
 
-/* Integer packing. */
+/* Unsigned integer packing. */
 #define DEFPACK_BE(bits, type) void pack_ ## bits ## _be ( \
 	unsigned char *out, type v \
 ) { \
@@ -56,7 +56,7 @@ DEFPACK_LE(64, unsigned long long)
 #endif
 
 #define DEFUNPACK_BE(bits, type) type unpack_ ## bits ## _be ( \
-	unsigned char *in \
+	const unsigned char *in \
 ) { \
 	type v = 0; \
 	unsigned i; \
@@ -68,7 +68,7 @@ DEFPACK_LE(64, unsigned long long)
 }
 
 #define DEFUNPACK_LE(bits, type) type unpack_ ## bits ## _le ( \
-	unsigned char *in \
+	const unsigned char *in \
 ) { \
 	type v = 0; \
 	unsigned i; \
@@ -90,3 +90,46 @@ DEFUNPACK_LE(32, unsigned long)
 #ifdef ULLONG_MAX
 DEFUNPACK_LE(64, unsigned long long)
 #endif
+
+/*
+ * Two's complement signed integer packing.  This is unlikely to work on
+ * systems that don't themselves use two's complement.
+ */
+
+#define DEFUNPACK_SBE(bits, max, type) type unpack_s ## bits ## _be ( \
+	const unsigned char *in \
+) { \
+	type v = 0; \
+	unsigned i; \
+	int sign = (in[0] & 0x80) ? 1 : 0; \
+	for (i = 0; i < bits/8; i++) { \
+		v *= 256; \
+		v += in[i] & (i == 0 ? 0x7f : 0xff); \
+	} \
+	return sign*(-max-1) + v; \
+}
+
+#define DEFUNPACK_SLE(bits, max, type) type unpack_s ## bits ## _le ( \
+	const unsigned char *in \
+) { \
+	type v = 0; \
+	unsigned i; \
+	int sign = (in[bits/8 - 1] & 0x80) ? 1 : 0; \
+	for (i = 1; i <= bits/8; i++) { \
+		v *= 256; \
+		v += in[bits/8 - i] & (i == 1 ? 0x7f : 0xff); \
+	} \
+	return sign*(-max-1) + v; \
+}
+
+DEFUNPACK_SBE(16, 32767, short)
+DEFUNPACK_SBE(32, 2147483647l, long)
+#ifdef LLONG_MAX
+DEFUNPACK_SBE(64, 9223372036854775807ll, long long)
+#endif
+
+DEFUNPACK_SLE(16, 32767, short)
+DEFUNPACK_SLE(32, 2147483647l, long)
+#ifdef LLONG_MAX
+DEFUNPACK_SLE(64, 9223372036854775807ll, long long)
+#endif