oasm: Add initial support for labels

A label is like a pin on a map with a number attached to it. OASM keeps track
of a number referred to as the psuedo instruction pointer (PIP). This value is
initially zero by default and is incremented every instruction. The purpose of
this value is to pin a location in the code and mark it to be at a specific address
so that further references to that label would be translated to the previous PIP value
at the time of encountering the label.

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

2 files changed, 5 insertions, 0 deletions

diff --git a/usr.bin/oasm/include/oasm/lex.h b/usr.bin/oasm/include/oasm/lex.h
index 62183e0..69e50a1 100644
--- a/usr.bin/oasm/include/oasm/lex.h
+++ b/usr.bin/oasm/include/oasm/lex.h
@@ -103,6 +103,7 @@ typedef enum {
     TT_INC,         /* 'inc' */
     TT_DEC,         /* 'dec' */
     TT_IMM,         /* #<n> */
+    TT_LABEL,       /* 'label: ...' */
 
     /* Register sets */
     __XN_REGS,      /* x0-x15 */
diff --git a/usr.bin/oasm/include/oasm/state.h b/usr.bin/oasm/include/oasm/state.h
index 5f58144..6dd2435 100644
--- a/usr.bin/oasm/include/oasm/state.h
+++ b/usr.bin/oasm/include/oasm/state.h
@@ -39,6 +39,8 @@
  * OASM state:
  *
  * @filename: Filname of unit we are parsing
+ * @pip: Pseudo instruction pointer
+ * @label_ip: IP at current label start
  * @in_fd: Input file descriptor
  * @out_fd: Resulting binary output file descriptor
  * @line: Current line number
@@ -46,6 +48,8 @@
  */
 struct oasm_state {
     char *filename;
+    off_t pip;
+    off_t label_ip;
     int in_fd;
     int out_fd;
     off_t line;