duskos

commit 014942e251ad4b732daf8319eee102e2a3140005
parent 6c38e0cb5299907fabdda579775df14588f1df1b
Author: Virgil Dupras <hsoft@hardcoded.net>
Date:   Sun,  2 Jul 2023 11:12:49 -0400

hal i386: fix [@+], and [!+], with A>) and m)

Diffstat:
M
fs/doc/hal.txt
 | 
5
++++-
M
fs/tests/hal.fs
 | 
11
+++++++++++
M
fs/xcomp/i386/kernel.fs
 | 
9
++++++---

3 files changed, 21 insertions(+), 4 deletions(-)
diff --git a/fs/doc/hal.txt b/fs/doc/hal.txt
@@ -74,7 +74,10 @@ i386 would yield "bx sp 4 +) lea, ax bx add,".
 The "&)" word never writes instructions directly, only operator words. The
 "lea," above wouldn't be written when "&)" is called, but when "+," is.
 
-The &) operand can't be used with: 8b) 16b) i)
+The &) operand always results in a 32-bit operation. Don't try to apply 16b) or
+8b) afterwards, this results in undefined behavior.
+
+&) can't be used with i).
 
 ### <>) operand modifiers
 
diff --git a/fs/tests/hal.fs b/fs/tests/hal.fs
@@ -251,4 +251,15 @@ code test27 ( a b c d -- a+d )
   PSP) 5 +) 3 +) +, nip, nip, nip, exit,
 
 20 54 12 22 test27 42 #eq
+
+create foo 42 , 54 ,
+create ptr foo ,
+\ [@+] with A>) and m)
+code test28 ( -- n )
+  ptr m) A>) [@+],
+  dup, A) &) @,
+  exit,
+
+test28 42 #eq
+test28 54 #eq
 testend
diff --git a/fs/xcomp/i386/kernel.fs b/fs/xcomp/i386/kernel.fs
@@ -291,7 +291,8 @@ pc to lblmodrmwr ( operand -- )
     $24 i) cwrite, forward! forward! \ mod=3 and rm=SP? write SIB
   dl al mov, dl $c0 i) and, \ dl=mod
   dl $40 i) cmp, L2 abs>rel jz, \ disp8
-  al $05 i) cmp, L3 abs>rel jz, \ m) means disp32
+  dl al mov, 0 dl reg!,
+  dl $05 i) cmp, L3 abs>rel jz, \ m) means disp32
   xdrop, ret,
 
 \ If HALDEREF flag is set operate the necessary changes in opmod to dereference
@@ -346,7 +347,9 @@ xcode !, ( operand -- )
 xcode @!, ( operand -- ) \ operand ax xchg,
   ax $8600 i) or, lblregularwr absjmp,
 
+\ TODO: this is broken with 16b) and 8b)
 xcode +n, ( n operand -- ) \ operand n i) add,
+  0 al reg!,
   si 0 d) 1 i) cmp, forward8 jnz,
     xnip, ax $fe00 i) or, lblregularwr absjmp, forward!
   si 0 d) -1 i) cmp, forward8 jnz,
@@ -405,8 +408,8 @@ pc to L2 ( operand -- operand-with-di-src )
   di al reg!,
   wcall, 32b) wcall, @,
   wcall, 32b) wcall, +n,
-  ax $20100 i) and, \ Set operand to W) but preserve size flags
-  al $07 i) mov, \ keep size, but modrm is for di 0 d) ax mov,
+  ax $20138 i) and, \ Set operand src but preserve size and dst
+  al $07 i) or, \ keep size, but modrm is for di 0 d) dst mov,
   ret,
 
 xcode [@+], ( operand -- )