add get_reg_bits and test, streamline ModRM calculations, correct opcodes, fix typos...

twasm/asm/tests.asm

@@ -40,6 +40,9 @@ run_tests:
   call clear_test_arena
   call test_get_opcode
 
+  call clear_test_arena
+  call test_get_reg_bits
+
   ret
   .msg db "running test suite...", 0x0A, 0x00
 
@@ -529,7 +532,7 @@ test_get_opcode:
 
   mov di, 0x0053 ; xor
   call get_opcode
-  cmp al, 0x33
+  cmp al, 0x31
   jne .fail
 
   mov di, 0x0054  ; inc
@@ -557,6 +560,42 @@ test_get_opcode:
     ret
   .msg db "test_get_opcode...", 0x00
 
+; ------------------------------------------------------------------------------
+; test_get_reg_bits
+;
+; description:
+; tests get_reg_bits described functionality
+; ------------------------------------------------------------------------------
+
+test_get_reg_bits:
+  mov rsi, .msg
+  call print
+
+  mov di, 0x0000    ; rax
+  call get_reg_bits
+  cmp al, 000b
+  jne .fail
+
+  mov di, 0x0010    ; eax
+  call get_reg_bits
+  cmp al, 000b
+  jne .fail
+
+  mov di, 0x0003    ; rdx
+  call get_reg_bits
+  cmp al, 010b
+  jne .fail
+
+  .pass:
+    mov rsi, msg_pass
+    call print
+    ret
+  .fail:
+    mov rsi, msg_fail
+    call print
+    ret
+  .msg db "test_get_reg_bits...", 0x00
+
 msg_pass:
   db 0x0A
   times (TEST_LINE_LENGTH + .start - .end) db " ", ; right align