Hi,
The jump table used in dc/bcode.c is technically off by one, which leads
to the following harmless inconsistency:
$ printf '\376' | dc
dc: \xfe (0376) is unimplemented
$ printf '\377' | dc
dc: internal error: opcode 255
This could be fixed by making it hold 256 entries instead of 255;
however, since all commands are ASCII characters, it actually could
instead be reduced to 128 entries, with a small adjustment of the
relevant check in the eval() function.
Index: bcode.c
===================================================================
RCS file: /cvs/src/usr.bin/dc/bcode.c,v
retrieving revision 1.51
diff -u -p -r1.51 bcode.c
--- bcode.c 26 Feb 2017 11:29:55 -0000 1.51
+++ bcode.c 17 Nov 2017 02:38:12 -0000
@@ -137,7 +133,7 @@ struct jump_entry {
opcode_function f;
};
-static opcode_function jump_table[UCHAR_MAX];
+static opcode_function jump_table[128];
static const struct jump_entry jump_table_data[] = {
{ ' ', nop },
@@ -238,7 +234,7 @@ init_bmachine(bool extended_registers)
if (bmachine.reg == NULL)
err(1, NULL);
- for (i = 0; i < UCHAR_MAX; i++)
+ for (i = 0; i < 128; i++)
jump_table[i] = unknown;
for (i = 0; i < JUMP_TABLE_DATA_SIZE; i++)
jump_table[jump_table_data[i].ch] = jump_table_data[i].f;
@@ -1746,10 +1716,10 @@ eval(void)
(void)fprintf(stderr, "%zd =>\n", bmachine.readsp);
#endif
- if (0 <= ch && ch < UCHAR_MAX)
+ if (0 <= ch && ch < 128)
(*jump_table[ch])();
else
- warnx("internal error: opcode %d", ch);
+ unknown();
#ifdef DEBUGGING
stack_print(stderr, &bmachine.stack, "* ",
Regards,
kshe
