duskos

commit df2a6f97cd432cbd79a6936abfd3c45691bf6c64
parent a680f1ecf8953f05f92d55ff0b508fb79dd03c5b
Author: Virgil Dupras <hsoft@hardcoded.net>
Date:   Thu, 21 Jul 2022 20:37:16 -0400

asm/i386: add the ability to MOV from/to segment registers

Diffstat:
M
fs/asm/i386.fs
 | 
16
+++++++++++++---

1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/fs/asm/i386.fs b/fs/asm/i386.fs
@@ -7,9 +7,12 @@
 4 const SP         5 const BP          6 const SI          7 const DI
 0 const AL         1 const CL          2 const DL          3 const BL
 4 const AH         5 const CH          6 const DH          7 const BH
+0 const ES         1 const CS          2 const SS          3 const DS
+4 const FS         5 const GS
 4 const SIB \ mod 0/1/2 + r/m 4 == SIB
 
 0 value op8b    \ is current op in 8bit mode?
+0 value opsreg  \ is current op an Sreg?
 1 value opdirec \ 1: reg=tgt r/m=src  0: reg=src r/m=tgt
 3 value opmod   \ by default, we're in "direct reg" mode
 -1 value opreg  \ -1 = unset
@@ -21,7 +24,8 @@
 0 value realmode
 
 \ Utilities
-: asm$ 0 to op8b 1 to opdirec 3 to opmod -1 to opreg -1 to oprm 0 to imm? ;
+: asm$ 0 to op8b 0 to opsreg 1 to opdirec 3 to opmod -1 to opreg -1 to oprm
+  0 to imm? ;
 : _err asm$ abort" argument error" ;
 : _assert not if _err then ;
 : w, here w! 2 allot ;
@@ -37,7 +41,8 @@
 : opreg! ( reg -- )
   opreg 0>= if
     oprm 0< _assert \ can't have a 2nd argument!
-    opreg to oprm then
+    opreg to oprm
+    0 to opdirec then
   to opreg ;
 
 : .asm ." 8b? " op8b . ."  d" opdirec . ."  mod " opmod . ."  reg " opreg .
@@ -106,6 +111,9 @@ AX _ ax   BX _ bx   CX _ cx   DX _ dx   SP _ sp   BP _ bp   SI _ si   DI _ di
 : _ doer ( reg -- ) c, does> c@ ( reg ) r! 1 to op8b ;
 AL _ al   BL _ bl   CL _ cl   DL _ dl   AH _ ah   BH _ bh   CH _ ch   DH _ dh
 
+: _ doer ( reg -- ) c, does> c@ ( reg ) opreg! 1 to opsreg ;
+ES _ es   SS _ ss   DS _ ds   FS _ fs   GS _ gs
+
 : i) ( imm -- ) 1 to imm? to imm ;
 
 : 16breg>[oprm] ( reg ) case
@@ -222,7 +230,9 @@ $58 op pop,        $50 op _push,
   imm? if opmod 3 = if \ mov reg, imm shortcut
       $b0 op8b not 3 lshift or ( b0 or b8 ) opreg or c, imm, asm$
     else $c7 c, 0 opreg! msd, imm, asm$ then
-  else $88 opmodrm, then ;
+  else
+    opsreg if $8c opdirec << or c, msd, asm$ else
+    $88 opmodrm, then then ;
 
 \ INT is special
 : int, ( n -- ) $cd c, c, ;