duskos

commit 772942e7deff99e73fd1fa9247293bd1a25cf9f5
parent dc69524d0f60680b6477ee932f7590048b3d2ce4
Author: Virgil Dupras <hsoft@hardcoded.net>
Date:   Fri,  7 Oct 2022 14:29:25 -0400

asm/i386: add loop, loopz, loopnz,

Diffstat:
M
fs/asm/i386.fs
 | 
4
++++
M
fs/xcomp/i386.fs
 | 
12
+++++-------

2 files changed, 9 insertions(+), 7 deletions(-)
diff --git a/fs/asm/i386.fs b/fs/asm/i386.fs
@@ -185,6 +185,10 @@ $4 op jz,        $5 op jnz,      $2 op jc,        $3 op jnc,
 $8 op js,        $9 op jns,      $c op jl,        $d op jnl,
 $7 op ja,        $6 op jna,
 
+: op ( opcode -- ) doer , does> ( rel a -- )
+  @ over jrel8? _assert op, jrel8, ;
+$e2 op loop,     $e1 op loopz,   $e0 op loopnz,
+
 \ JMP and CALL
 \ These are special. They can either be called with a modrm tgt, or with *no
 \ argument at all*. In the latter case, an absolute addr to call is waiting on
diff --git a/fs/xcomp/i386.fs b/fs/xcomp/i386.fs
@@ -645,18 +645,18 @@ xcode EMIT
   lblemit pspushN,
   ret,
 
-\ TODO: support case where u=0
 xcode rtype ( a u -- )
   CX SI pspop2,
 pc to lblrtype
+  cx cx test,
+  lblret abs>rel jz,
   al [esi] movclr,
   AX pspush,
   si push, cx push,
   lblemit m) call,
   cx pop, si pop,
   si inc,
-  cx dec,
-  lblrtype abs>rel jnz,
+  lblrtype abs>rel loop,
   ret,
 
 \ During early boot, it's better to halt the machine than to go back to the
@@ -848,8 +848,7 @@ L2 forward! \ parse ok
   ax 4 i) shl,     \ res*16
   ax bx add,
   si inc,
-  cx dec,
-  ( pc ) abs>rel jnz, ( loop )
+  ( pc ) abs>rel loop, ( loop )
   [ebp] ax mov,
   1 pspushN,
   ret,
@@ -868,8 +867,7 @@ pc ( loop )
   L1 abs>rel jnc,   \ fail
   ax bx add,
   si inc,
-  cx dec,
-  ( pc ) abs>rel jnz, ( loop )
+  ( pc ) abs>rel loop, ( loop )
   [ebp] ax mov,
   1 pspushN,
   ret,