Handle is4 bytes without meaningful information in the bottom bits

Support is4 bytes without meaningful information in the bottom bits.
This is equivalent to /is4=0 for the assembler, but makes the bottom
bits don't care for the disassembler.

1 files changed, 7 insertions, 3 deletions

diff --git a/insns.pl b/insns.pl
index 5b45d7e..8199732 100644
--- a/insns.pl
+++ b/insns.pl
@@ -687,10 +687,14 @@ sub byte_code_compile($) {
 	    }
 	    $prefix_ok = 0;
 	} elsif ($op eq '/is4') {
-	    if (!defined($oppos{'i'} || !defined($oppos{'s'}))) {
-		die "$0: $line: $op without 'i' and 's' operands\n";
+	    if (!defined($oppos{'s'})) {
+		die "$0: $line: $op without 's' operand\n";
+	    }
+	    if (defined($oppos{'i'})) {
+		push(@codes, 0172, ($oppos{'s'} << 3)+$oppos{'i'});
+	    } else {
+		push(@codes, 0174, $oppos{'s'});
 	    }
-	    push(@codes, 0172, ($oppos{'s'} << 3)+$oppos{'i'});
 	    $prefix_ok = 0;
 	} elsif ($op =~ /^\/is4\=([0-9]+)$/) {
 	    my $imm = $1;