From cfcc77e723ccb9aa023e35d3d0172161d4907bed Mon Sep 17 00:00:00 2001
From: "Jakob L. Kreuze" <zerodaysfordays@sdf.lonestar.org>
Date: Fri, 27 Dec 2019 16:49:08 -0500
Subject: Implement syntax for address/label dereferencing.

---
 asm.myr | 50 ++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 38 insertions(+), 12 deletions(-)

diff --git a/asm.myr b/asm.myr
index dda4eed..250f242 100644
--- a/asm.myr
+++ b/asm.myr
@@ -40,6 +40,8 @@ type literal = union
     `Number int
     `Register int
     `Label byte[:]
+    `DerefAddr int
+    `DerefLabel byte[:]
     `Invalid
 ;;
 
@@ -48,16 +50,23 @@ const getnum = {s
 }
 
 const parselit = {s
-    if s[0] == ('#' : byte)
+    if s.len < 1
+        -> `Invalid
+    elif s[0] == ('#' : byte)
         match getnum(s)
         |`std.Some(n): -> `Number(n)
         |`std.None: -> `Invalid
         ;;
-    elif s[0] == ('v' : byte)
+    elif s[0] == ('v' : byte) || s[0] == ('V' : byte)
         match getnum(s)
         |`std.Some(n): -> `Register(n)
         |`std.None: -> `Invalid
         ;;
+    elif s[0] == ('[' : byte)
+        match getnum(s[:s.len-1])
+        |`std.Some(n): -> `DerefAddr(n)
+        |`std.None: -> `DerefLabel(s[:s.len-1])
+        ;;
     else
         -> `Label(s)
     ;;
@@ -82,25 +91,42 @@ const emitinstr = {p
         ;;
         match parselit(p[1])
         | `Number(n): b = `std.Some([0x00 | (n & 0x0f00), (n & 0xff)])
-        | `Label(l): b = `std.Some([0x20, 0x00])
+        | `Label(l): b = `std.Some([0x00, 0x00])
             mark = `std.Some(strdup(l))
-        | `Register(_):
-            -> `std.Err("SYS called with register instruction")
-        | `Invalid:
-            -> `std.Err(std.fmt("invalid literal {}", p[1]))
+        | _:
+            -> `std.Err(std.fmt("invalid argument to SYS: {}", p[1]))
         ;;
     | "CALL":
         if p.len < 2
             -> `std.Err("CALL missing subroutine address")
         ;;
         match parselit(p[1])
-        | `Number(n): b = `std.Some([0x00 | (n & 0x0f00), (n & 0xff)])
+        | `Number(n): b = `std.Some([0x20 | (n & 0x0f00), (n & 0xff)])
         | `Label(l): b = `std.Some([0x20, 0x00])
             mark = `std.Some(strdup(l))
-        | `Register(_):
-            -> `std.Err("CALL called with register instruction")
-        | `Invalid:
-            -> `std.Err(std.fmt("invalid literal {}", p[1]))
+        | _:
+            -> `std.Err(std.fmt("invalid argument to CALL: {}", p[1]))
+        ;;
+    | "JP":
+        if p.len < 2
+            -> `std.Err("JP missing address")
+        elif p.len == 2
+            match parselit(p[1])
+            | `Number(n): b = `std.Some([0x10 | (n & 0x0f00), (n & 0xff)])
+            | `Label(l): b = `std.Some([0x10, 0x00])
+                mark = `std.Some(strdup(l))
+            | _:
+                -> `std.Err(std.fmt("invalid argument to JP: {}", p[1]))
+            ;;
+        else
+            match (parselit(p[1]), parselit(p[2]))
+            | (`Register(0), `Number(n)):
+                b = `std.Some([0xb0 | (n & 0x0f00), (n & 0xff)])
+            | (`Register(0), `Label(l)): b = `std.Some([0xb0, 0x00])
+                mark = `std.Some(strdup(l))
+            | _:
+                -> `std.Err(std.fmt("invalid arguments to JP: {}, {}", p[1], p[2]))
+            ;;
         ;;
     | _:
         -> `std.Err("unrecognized instruction")
-- 
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