add trim_trailing_whitespace

twasm/asm/main.asm

@@ -648,13 +648,15 @@ tokenise:
     je .operand_break
     cmp dl, 0x00
     je .operand_break
+    cmp dl, ";"
+    je .operand_break
 
     inc rax ; inc length counter
     inc rdi ; inc byte pointer
     jmp .operand_loop
 
   .operand_break:
-    pop rdi  ; rdi = first byte of operand
+    pop rdi  ; rdi -> first byte of operand
     push rdi
     push rsi
     mov rsi, rax ; rsi = length of operand in bytes
@@ -747,7 +749,8 @@ tokenise:
 ;
 ; | code | rsi contents         | notes |
 ; |------|----------------------|-------|
-; | 0x00 | token ID of register |       |
+; | 0x00 | token ID of register | reg   |
+; | 0x10 | token ID of register | [reg] |
 ; | 0xFF | -                    | error |
 ;
 ; parameters:
@@ -760,10 +763,27 @@ tokenise:
 ; ------------------------------------------------------------------------------
 
 evaluate_operand:
-  cmp rsi, 4
+  push rdi
-  jg .unrecognised
+
+  push rsi
+  mov rsi, rdi ; rsi -> start of operand
+  pop rdi      ; rdi = size of operand
+  call trim_trailing_whitespace
+
+  pop rdi      ; rdi -> first byte of operand
+  mov rsi, rax ; rsi = size of operand w/o trailing whitespace
+
+  cmp [rdi + 1], '['
+  je .address
+
+  jmp .register
+
+  .address:
+    jmp halt
 
   .register:
+    cmp rsi, 4
+    jg .unrecognised
     push rdi
     mov edi, [rdi] ; edi = register to be searched
 
@@ -779,6 +799,10 @@ evaluate_operand:
     je .register1
   .register1:
     and edi, 0xFF
+    push rsi
+    mov rsi, .msg
+    call print.debug
+    pop rsi
   .register2:
     and edi, 0xFFFF
   .register3:
@@ -798,6 +822,7 @@ evaluate_operand:
   .unrecognised:
     mov dl, 0xFF
     ret
+  .msg db "evaluate_operand", 0x0A, 0x00
 
 ; ------------------------------------------------------------------------------
 ; evaluate_constant
@@ -1174,6 +1199,47 @@ elemb:
     mov rax, 1 ; return 1; dl an element of list
     ret
 
+; ------------------------------------------------------------------------------
+; trim_trailing_whitespace
+;
+; description:
+; trims whitespace from the start and end of the given byte array.
+;
+; parameters:
+; rdi = size of list
+; rsi -> start of list
+;
+; returned:
+; rax = new size of list
+; ------------------------------------------------------------------------------
+
+trim_trailing_whitespace:
+  cmp rdi, 0 ; list of length zero
+  je .done   ; already trimmed
+
+  push rdi
+  push rsi
+
+  mov dl, [rsi + rdi - 1] ; last element of given list
+  mov rsi, whitespace_3   ; pointer of whitespace list
+  mov rdi, 3              ; length of whitespace list
+  call elemb
+
+  pop rsi ; rsi -> start of list
+  pop rdi ; rdi = size of list
+
+  cmp al, 0 ; if last element whitespace
+  je .done  ; then break
+
+  .trim     ; otherwise one shorter
+    dec rdi
+    call trim_trailing_whitespace
+    ret
+
+  .done
+    mov rax, rdi
+    ret
+
 ; ------------------------------------------------------------------------------
 ; clear_token_table
 ;
@@ -1484,6 +1550,5 @@ program:
   db "inc rax ; inline comment", 0x0A
   db "; one line comment", 0x0A
   db "mov [ rax ], rdx", 0x0A
-  db "hlt"
+  db "hlt", 0x00 ; for the sake of being able to print it, I made it a string
-  db 0x00 ; just for the sake of being able to print it, I made it a string
   .size db $ - program