pack: Simplify signed integer packing calculation

Because of the fact that uintmax_t guarantees at least a full 64 bit
width and because of C's behavior when a signed type is converted to an
unsigned type and the value is out of range, the new code just
sign-extends and converts to a uintmax_t wide two's complement signed
value.

As an aside, the old code was written forgetting the fact that that
uintmax_t + intmax_t would be first converted to uintmax_t + uintmax_t
before being evaluated. The end result was the same except it ended up
being offset by 2^8s.

1 files changed, 1 insertions, 7 deletions

diff --git a/pack.c b/pack.c
index 4a8228a..5a603e0 100644
--- a/pack.c
+++ b/pack.c
@@ -59,13 +59,7 @@ enum pack_status pack(void *buf_, size_t size, const char *fmt, ...)
 		if (sign) {
 			intmax_t n = v.signed_;
 			tr_debug("val.s: %" PRIdMAX, v.signed_);
-			if (v.signed_ >= 0) {
-				v.unsigned_ = n;
-			} else {
-				uintmax_t offt = BITMASK(s * 8);
-				n += 1;
-				v.unsigned_ = offt + n;
-			}
+			v.unsigned_ = n;
 		}
 		tr_debug("val.u: %" PRIuMAX, v.unsigned_);
 		write_val(&buf[offset], s, endianness, v.unsigned_);