reformat, add copy_token and test, fix bug

twasm/asm/main.asm

@@ -15,38 +15,49 @@ OUTPUT_SIZE equ 0x1000     ; max length of outputed binary
 start:
   mov rsi, msg_welcome
   call print
-
+ 
   call run_tests
 
   jmp halt
 
-;
+; ------------------------------------------------------------------------------
 ; tokenising
-;
+; ------------------------------------------------------------------------------
 
+; ------------------------------------------------------------------------------
 ; copy_token 
 ;
 ; description:
 ; copies a token from one spot in memory to another
-; and returns metadata about that token
 ;
 ; parameters:
-; rdi -> start of asm command to be read
+; rdi -> start of buffer to be read
 ; rsi -> start of buffer to be written
 ;
 ; returned:
+; rax -> last byte read
+; rdx -> last byte written
+; ------------------------------------------------------------------------------
+
 copy_token:
-  mov rax, rdi
   .loop:
+    mov al, [rdi] ; check if next char is a space
     cmp al, " "
-    je .continue
-    jne .break
-    .continue:
-      call copy_byte
+    je .break
+
+    call copy_byte ; copy the next byte if not
+
+    inc rdi ; increment read- and write-pointers
+    inc rsi
+    jmp .loop ; and loop again
+
   .break:
-    inc rax
-  ret
+    mov rax, rdi ; return values
+    mov rdx, rsi
+    ret
+  .msg db "yo loop copy_token", 0x0D, 0x0A, 0x00
     
+; ------------------------------------------------------------------------------
 ; copy_byte
 ;
 ; description:
@@ -57,16 +68,20 @@ copy_token:
 ; rsi -> word to be written
 ;
 ; returned:
-; al = byte that was read
+; rax = byte that was read
+; ------------------------------------------------------------------------------
+
 copy_byte:
+  xor rax, rax ; zero out so it returns fine
   mov al, [rdi]
   mov [rsi], al
   ret
 
-; 
+; ------------------------------------------------------------------------------
 ; utilities
-; 
+; ------------------------------------------------------------------------------
 
+; ------------------------------------------------------------------------------
 ; print
 ;
 ; description:
@@ -74,8 +89,11 @@ copy_byte:
 ;
 ; parameters:
 ; rsi -> start of null-terminated string
-; dx = port to output to
+; ------------------------------------------------------------------------------
+
 print:
+  push rdx
+  mov rdx, 0x3F8
   .loop:
     mov al, [rsi]
     test al, al
@@ -84,47 +102,50 @@ print:
     inc rsi
     jmp .loop
   .done:
+    pop rdx
     ret
 
+; ------------------------------------------------------------------------------
 ; halt
 ;
 ; description:
 ; halts the program, silly :)
+; ------------------------------------------------------------------------------
+
 halt:
   mov rsi, msg_halt
   call print
   hlt
   jmp halt
 
-;
+; ------------------------------------------------------------------------------
 ; tests
-;
+; ------------------------------------------------------------------------------
 
+; ------------------------------------------------------------------------------
 ; run_tests
 ;
 ; description:
 ; runs all tests
-;
-; parameters:
-; dx = port to output to
+; ------------------------------------------------------------------------------
+
 run_tests:
   mov rsi, .msg
   call print
 
   call test_copy_byte
+  call test_copy_token
 
   ret
   .msg db "running test suite...", 0x0D, 0x0A, 0x00
 
+; ------------------------------------------------------------------------------
 ; test_copy_byte
 ;
 ; description:
-; makes sure copy_byte function works by testing the following
-; - that it copies one byte to a specified memory address
-; - that it returns the copied byte in al
-;
-; parameters:
-; dx = port to output to
+; tests copy_byte's described functionality
+; ------------------------------------------------------------------------------
+
 test_copy_byte:
   mov rsi, .msg
   call print
@@ -134,9 +155,12 @@ test_copy_byte:
   call copy_byte
 
   mov cx, [rsi]
+  and ax, 0xFF ; only compare bottom byte
+  and cx, 0xFF
   cmp ax, cx ; compare returned byte to copied byte
   jne .fail
-  je .pass
+  cmp al, [test_byte] ; compare returned byte to expected byte
+  jne .fail
 
   .pass:
     mov rsi, msg_pass
@@ -148,9 +172,45 @@ test_copy_byte:
     ret
   .msg db "test_copy_byte...", 0x00
 
+; ------------------------------------------------------------------------------
+; test_copy_token
 ;
+; description:
+; tests copy_token described functionality
+; ------------------------------------------------------------------------------
+
+test_copy_token:
+  mov rsi, .msg
+  call print
+
+  mov rdi, test_token      ; read buffer
+  mov rsi, TEST_ARENA_ADDR ; write buffer
+  call copy_token
+
+  ; check reported final indicies with the expected final indicies
+  cmp rax, test_token + 8 ; last byte read
+  jne .fail
+  cmp rdx, TEST_ARENA_ADDR + 8 ; last byte written
+  jne .fail
+
+  mov rsi, TEST_ARENA_ADDR
+  mov rcx, [rsi]
+  cmp rcx, [test_token] ; compare copied token to expected token
+  jne .fail
+
+  .pass:
+    mov rsi, msg_pass
+    call print
+    ret
+  .fail:
+    mov rsi, msg_fail
+    call print
+    ret
+  .msg db "test_copy_token...", 0x00
+
+; ------------------------------------------------------------------------------
 ; data
-;
+; ------------------------------------------------------------------------------
 
 msg_welcome db "Welcome to Twasm", 0x0D, 0x0A, 0x00
 msg_halt db "halted.", 0x0D, 0x0A, 0x00
@@ -158,4 +218,4 @@ msg_pass db "passed.", 0x0D, 0x0A, 0x00
 msg_fail db "failed.", 0x0D, 0x0A, 0x00
 
 test_byte db "T"
-test_token db "Test Token" ; two tokens, one followed by a space and one by nothing
+test_token db "TestTokn " ; followed by space. Quad word