add octal

twasm/asm/main.asm

@@ -626,7 +626,7 @@ tokenise:
 
     jmp .operator_id_loop
 
-  .found_id
+  .found_id:
     push rdx
     mov dx, [rcx + 4] ; dx = token id
 
@@ -730,6 +730,7 @@ tokenise:
 ; | type | p. | description  |
 ; |------|----|--------------|
 ; | 0x00 | 0x | hexidecimal  |
+; | 0x01 | 0b | octal        |
 ; | 0xFF |    | unrecognised |
 ;
 ; where `p.` is the prefix
@@ -744,24 +745,38 @@ tokenise:
 ; ------------------------------------------------------------------------------
 
 evaluate_constant:
+                ; rsi = number of bytes left
+                ; rdi -> current byte of constant
+  xor eax, eax  ; rax = value of constant
+
   ; TODO fix this cheap trick xD
   mov dl, [rdi]
+  dec rsi ; one fewer byte left
+  inc rdi ; point to next byte
   cmp dl, '0'
   jne .unrecognised
-  dec rsi ; one fewer byte left
-  inc rdi ; point to next byte
 
   mov dl, [rdi]
-  cmp dl, 'x'
-  jne .unrecognised
   dec rsi ; one fewer byte left
   inc rdi ; point to next byte
 
-               ; rsi = number of bytes left
-               ; rdi -> current byte of constant
-  xor eax, eax ; rax = value in hex of constant
+  ; hex case
+  mov rcx, 0x00
+  push rcx
+  cmp dl, 'x'
+  je .hex_loop
+  pop rcx
 
-  .loop:
+  ; octal case
+  mov rcx, 0x01
+  push rcx
+  cmp dl, 'q'
+  je .oct_loop
+  pop rcx
+
+  jmp .unrecognised
+
+  .hex_loop:
     cmp rsi, 0 ; make sure we're in range
     je .break  ; if not, break
 
@@ -772,24 +787,43 @@ evaluate_constant:
     sub dl, '0' ; dl = if digit: digit; else :shrug:
 
     cmp dl, 9     ; if !digit:
-    jg .alpha     ;   letter
-    jmp .continue ; else loop
+    jg .hex_alpha     ;   letter
+    jmp .hex_continue ; else loop
 
-  .alpha
+  .hex_alpha:
     sub dl, 7        ; map [('A'-'0')..('F'-'0')] to [0xA..0xF]
     cmp dl, 0xF      ; if not in the range [0xA..0xF]
     jg .unrecognised ; then unrecognised
 
-  .continue
+  .hex_continue:
     and dl, 0x0F ; mask
     or al, dl    ; and add newest nibble
 
     dec rsi   ; one fewer byte left
     inc rdi   ; point to next byte
-    jmp .loop ; and loop
+    jmp .hex_loop ; and loop
+
+  .oct_loop:
+    cmp rsi, 0 ; make sure we're in range
+    je .break  ; if not, break
+
+    shl rax, 3 ; make room for next octal digit
+
+    mov dl, [rdi] ; dl = next byte of constant
+
+    sub dl, '0'
+    cmp dl, 7
+    jg .unrecognised
+
+    and dl, 7 ; mask
+    or al, dl ; and add newest 3-bit group
+
+    dec rsi       ; one fewer byte left
+    inc rdi       ; point to next byte
+    jmp .oct_loop ; and loop
 
   .break:
-    mov rdx, 0x00 ; hex type
+    pop rdx
     ret
 
   .unrecognised: