add warn print, clean up a little

twasm/asm/main.asm

@@ -24,6 +24,9 @@ TEST_LINE_LENGTH equ 80 ; right border of test suite results
 
 [bits 64]
 [org LOAD_ADDR]
+[default abs]   ; TODO see if I actually need to do this
+                ; afaik absolute addressing is not harmful on bare metal
+                ; reasoning: stops annoying warning =D
 
 start:
   mov rsp, STACK_ADDR ; we might need more stack space, let's just be safe
@@ -117,7 +120,7 @@ assemble:
     ; di = next tte
     call get_opcode
     ; al = opcode
-    mov [.pending_operator_opcode], al ; save it fttb
+    mov [.pending_operator_opcode], al ; save opcode fttb
     pop rdi
 
     pop rax ; from start of label .operator
@@ -139,7 +142,11 @@ assemble:
                                              ; of 2 args, it could also be the
                                              ; last of 1
 
-    ; otherwise, quietly discard the token, reset things, and keep going :/
+    ; otherwise, discard the token, reset things, and keep going :/
+    push rsi
+    mov rsi, .warn_unexpected_register
+    call print.warn
+    pop rsi
     call .reset_state
     jmp .continue_register
 
@@ -189,6 +196,10 @@ assemble:
   .break:
     ret
 
+  ; constants
+
+  .warn_unexpected_register db "ignoring unexpected register", 0x0A, 0x00
+
   ; procedures
 
   ; al = byte to write
@@ -200,7 +211,7 @@ assemble:
     ret
 
   ; runs dec on .pending_operator_num_args
-  .dec_num_args
+  .dec_num_args:
     push rax
     mov al, [.pending_operator_num_args]
     dec al
@@ -208,12 +219,12 @@ assemble:
     pop rax
     ret
 
-  .reset_state
+  .reset_state:
-    ; I don't actually know if these `word` and `byte` directives are needed
+    ; I don't actually know if these `word` directives are needed
     ; TODO check that. I think they are, becasue Nasm doesn't record the size
     ; of labels?
     mov word [.pending_operator_opcode], UNRECOGNISED_TOKEN_ID
-    mov byte [.pending_operator_num_args], 0x00
+    mov [.pending_operator_num_args], 0x00
     mov word [.first_argument], UNRECOGNISED_TOKEN_ID
     ret
 

twasm/package.nix

@@ -10,7 +10,11 @@ stdenv.mkDerivation {
   version = "0.1.0";
   src = ./.;
   buildPhase = ''
-    ${nasm}/bin/nasm asm/main.asm -o out.bin
+    ${nasm}/bin/nasm \
+      asm/main.asm \
+      -o out.bin \
+      -w+all \
+      -w-reloc-abs
   '';
   installPhase = ''
     dd if=/dev/zero of=disk bs=512 count=2880