parsefields: fix padding calculation

This was causing issues with aggregate types. A simple reproduction is:

type :type.1 = align 8 { 24 }
type :type.2 = align 8 { w 1, :type.1 1 }

The size of type.2 should be 32, adding only 4 bytes of padding between
the first and second field. Prior to this patch, 20 bytes of padding was
added instead, causing the type to have a size of 48.

Signed-off-by: Drew DeVault <[email protected]>

1 files changed, 2 insertions, 2 deletions

diff --git a/parse.c b/parse.c
index a7e4452..43ae23b 100644
--- a/parse.c
+++ b/parse.c
@@ -867,9 +867,9 @@ parsefields(Field *fld, Typ *ty, int t)
 		}
 		if (a > al)
 			al = a;
-		a = sz & (s-1);
+		a = (1 << a) - 1;
+		a = ((sz + a) & ~a) - sz;
 		if (a) {
-			a = s - a;
 			if (n < NField) {
 				/* padding */
 				fld[n].type = FPad;