oasm: Introduce encoding for the NOP instruction

The NOP (no operation) instruction simply tells the processor to do nothing.
This can be useful for various things such as padding, timing, etc.

--
nop
nop
nop
...
--

Signed-off-by: Ian Moffett <ian@osmora.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/usr.bin/oasm/lex.c b/usr.bin/oasm/lex.c
index dcd7c1f..fea9dc3 100644
--- a/usr.bin/oasm/lex.c
+++ b/usr.bin/oasm/lex.c
@@ -40,6 +40,7 @@
 static char putback = '\0';
 
 /* Instruction mnemonic strings */
+#define S_IMN_NOP  "nop"
 #define S_IMN_MOV  "mov"
 #define S_IMN_ADD  "add"
 #define S_IMN_SUB  "sub"
@@ -372,6 +373,13 @@ lex_tok(struct oasm_state *state, struct oasm_token *ttp)
             return 0;
         }
 
+        /* No operation? */
+        if (strcmp(p, S_IMN_NOP) == 0) {
+            ttp->type = TT_NOP;
+            ttp->raw = p;
+            return 0;
+        }
+
         /* Arithmetic operation? */
         if ((tok = token_arith(p)) != TT_UNKNOWN) {
             ttp->type = tok;