add get_direct_addressing_ModRM and test_*, fix a couple bugs/typos, add 'reg value' as register metadata

1 files changed, 72 insertions, 12 deletions

diff --git a/twasm/asm/main.asm b/twasm/asm/main.asm
index 57af625..1dfad3b 100644
--- a/twasm/asm/main.asm
+++ b/twasm/asm/main.asm
@@ -188,6 +188,63 @@ get_tte_typed_metadata:
     ret
 
 ; ------------------------------------------------------------------------------
+; get_direct_addressing_ModRM
+;
+; description:
+; given 2 register tokens, returns the ModR/M byte in direct addressing
+; (mod = 11b) mode
+;
+; parameters:
+; di = token table entry `reg`
+; si = token table entry `R/M`
+;
+; returned:
+; al = ModR/M byte
+; ------------------------------------------------------------------------------
+
+get_direct_addressing_ModRM:
+  ; TODO something is backwards in this function but I don't see it. If the test
+  ; suite fails, it's too far gone; rewrite it.
+  push rdi
+  push rsi
+  ; get metadata of reg
+  call get_tte_typed_metadata
+  ; al = typed metadata of reg
+  pop rsi
+  pop rdi
+
+  mov bl, al ; bl = metadata of reg
+
+  push rdi
+  push rsi
+  push rbx
+
+  ; get metadata of R/M
+  mov di, si
+  call get_tte_typed_metadata
+  ; al = typed metadata of R/M
+
+  pop rbx
+  pop rsi
+  pop rdi
+
+  mov dl, al
+
+  shr dl, 2
+  and dl, 111b ; mask
+
+  shr bl, 2
+  and bl, 111b ; mask
+  shl bl, 3
+
+  xor eax, eax
+  or al, 11b << 6 ; mod bits
+  or al, dl ; reg bits
+  or al, bl ; R/M bits
+  and rax, 0xFF ; mask for byte
+  ret
+
+; ------------------------------------------------------------------------------
 ; tokenising
 ; ------------------------------------------------------------------------------
 
@@ -872,30 +929,33 @@ tokens:
     dw 0x0059
   .by_name_5:
   .by_id:
+    dw 0x0010    ; eax
+    db 0x02      ; type: register
+    db 00000010b ; reg: 000b
+                 ; width: 10b (32 bits)
+
+    dw 0x0000    ; rax
+    db 0x02      ; type: register
+    db 00000011b ; reg: 000b
+                 ; width: 11b (64 bits)
+
+    dw 0x0003    ; rdx
+    db 0x02      ; type: register
+    db 00001011b ; reg: 010b
+                 ; width: 11b (64 bits)
+
     dw 0x0053 ; xor
     db 0x01   ; type: operator
     db 0x02   ; # operands
 
-    dw 0x0010 ; eax
-    db 0x02   ; type: register
-    db 0x02   ; width: 32 bit
-
     dw 0x0054 ; inc
     db 0x01   ; type: operator
     db 0x01   ; # operands
 
-    dw 0x0000 ; rax
-    db 0x02   ; type: register
-    db 0x03   ; width: 64 bit
-
     dw 0x0056 ; mov
     db 0x01   ; type: operator
     db 0x02   ; # operands
 
-    dw 0x0003 ; rdx
-    db 0x02   ; type: register
-    db 0x03   ; width: 64 bit
-
     dw 0x004F ; hlt
     db 0x01   ; type: operator
     db 0x00   ; # operands