libupkg: Add signed integer unpacking to fix incorrect signedness issue.

[upkg.git] / src / pack.c

diff --git a/src/pack.c b/src/pack.c
index b87ac34740f1e1b52e943381d87ea155a7f0422f..e711de19dcb50722d0f5a3e1362c45f31eff1de0 100644 (file)
--- 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 \
 ) { \
@@ -90,3 +90,48 @@ 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 ( \
+       unsigned char *in \
+) { \
+       type v = 0; \
+       unsigned i; \
+       int sign = (in[0] & 0x80) ? 1 : 0; \
+       in[0] &= 0x7f; \
+       for (i = 0; i < bits/8; i++) { \
+               v *= 256; \
+               v += in[i]; \
+       } \
+       return sign*(-max-1) + v; \
+}
+
+#define DEFUNPACK_SLE(bits, max, type) type unpack_s ## bits ## _le ( \
+       unsigned char *in \
+) { \
+       type v = 0; \
+       unsigned i; \
+       int sign = (in[bits/8 - 1] & 0x80) ? 1 : 0; \
+       in[bits/8 - 1] &= 0x7f; \
+       for (i = 1; i <= bits/8; i++) { \
+               v *= 256; \
+               v += in[bits/8 - i]; \
+       } \
+       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