duskos

commit fbabbf4b2048261a8fad01ed9e789dfb94a37d1a
parent c9a4ed1808b072963a5a8104a06eb1c66415d7f4
Author: Virgil Dupras <hsoft@hardcoded.net>
Date:   Fri, 15 Jul 2022 10:50:16 -0400

asm/i386: add d) support to sp register

Diffstat:
M
fs/asm/i386.fs
 | 
22
+++++++++++++++-------
M
fs/tests/asm/i386.fs
 | 
11
+++++++++++

2 files changed, 26 insertions(+), 7 deletions(-)
diff --git a/fs/asm/i386.fs b/fs/asm/i386.fs
@@ -8,6 +8,7 @@
 0 const AL         1 const CL          2 const DL          3 const BL
 4 const AH         5 const CH          6 const DH          7 const BH
 5 const MEM \ mod 0 + r/m 5 == abs memory
+4 const SIB \ mod 0/1/2 + r/m 4 == SIB
 
 \ Size modes
 0 const SZ32
@@ -22,6 +23,7 @@ SZ32 value opsz
 0 value imm? \ are we in immediate mode?
 0 value imm \ value of current immediate, if set
 0 value disp \ displacement value
+0 value sib \ value of the SIB byte
 
 \ Utilities
 : asm$ SZ32 to opsz 1 to opdirec 3 to opmod -1 to opreg -1 to oprm 0 to imm? ;
@@ -51,6 +53,9 @@ SZ32 value opsz
 : modrm, ( -- ) \ write down modrm, errors out if not all parts are there.
   opmod 3 lshift opreg or 3 lshift oprm or dup $100 < _assert c, ;
 
+: sib, ( -- ) \ write down the SIB byte if needed.
+  oprm SIB = opmod 3 < and if sib c, then ;
+
 : disp, ( -- ) \ write down displacement if needed.
   opmod case
     0 of = oprm MEM = if disp , then endof
@@ -58,6 +63,8 @@ SZ32 value opsz
     2 of = disp , endof
   endcase ;
 
+: msd, modrm, sib, disp, ;
+
 : imm, ( -- ) \ write down an immediate
   imm opsz case
     SZ32 of = , endof
@@ -67,11 +74,11 @@ SZ32 value opsz
   endcase ;
 
 : opmodrm, ( opcode -- ) \ write the operation in "modrm" mode
-  op, modrm, disp, asm$ ;
+  op, msd, asm$ ;
 
 : opimm, ( opcode opreg -- ) \ write the operation in "immediate" mode
   0 to opdirec \ TODO: allow sign-extend by making this logic variable
-  opreg! op, modrm, disp, imm, asm$ ;
+  opreg! op, msd, imm, asm$ ;
 
 \ Setting arguments
 
@@ -112,9 +119,10 @@ AL _ al   BL _ bl   CL _ cl   DL _ dl   AH _ ah   BH _ bh   CH _ ch   DH _ dh
     -1 to opreg
     0 to opdirec
   then
+  oprm SP = if $24 to sib then \ special case for ESP
   disp case
     of not oprm MEM = to opmod endof \ mod = 0 except if rm==MEM
-    $100 of > 1 to opmod endof
+    of isbyte? 1 to opmod endof
     2 to opmod
   endcase ;
 
@@ -176,11 +184,11 @@ $240420 op and,    $0c0108 op or,      $340630 op xor,
 \ Shifts. They come in 2 versions. The "naked" version is imm-only. The "cl"
 \ versions has CL as an inherent argument.
 : op ( opcode -- ) doer , does> @ dup 8 rshift ( opcode opreg )
-  imm? _assert opreg! c, modrm, disp, imm c, asm$ ;
+  imm? _assert opreg! c, msd, imm c, asm$ ;
 $04c1 op shl,         $05c1 op shr,
 
 : op ( opcode -- ) doer , does> @ dup 8 rshift ( opcode opreg )
-  imm? not _assert opreg! c, modrm, disp, asm$ ;
+  imm? not _assert opreg! c, msd, asm$ ;
 $04d3 op shlcl,         $05d3 op shrcl,
 
 \ Push/Pop
@@ -190,13 +198,13 @@ $58 op pop,        $50 op _push,
 
 \ PUSH can also push an immediate
 : push, imm? if
-    imm isbyte? if $6a c, SZ8 to opsz else $68 c, then imm, asm$ else
+    opsz SZ8 = if $6a else $68 then c, imm, asm$ else
     _push, then ;
 
 \ MOV has this special reg<-imm shortcut
 : mov,
   imm? if opmod 3 = if \ mov reg, imm shortcut
       $b0 opsz SZ8 = not 3 lshift or ( b0 or b8 ) opreg or c, imm, asm$
-    else $c7 c, 0 opreg! modrm, disp, imm, asm$ then
+    else $c7 c, 0 opreg! msd, imm, asm$ then
   else $88 opmodrm, then ;
 
diff --git a/fs/tests/asm/i386.fs b/fs/tests/asm/i386.fs
@@ -71,4 +71,15 @@ code foo7
   ret,
 
 foo7 42 #eq
+
+\ ESP+disp
+code foo8
+  42 i) push,
+  ax sp 0 d) mov,
+  sp 4 i) add,
+  bp 4 i) sub,
+  bp 0 d) ax mov,
+  ret,
+
+foo8 42 #eq
 testend