From Lucho: no need to preserve ebx

git-svn-id: https://svn.code.sf.net/p/freedos/svn/kernel/trunk@964 6ac86273-5f31-0410-b378-82cca8765d1b

hdr/stacks.inc

@@ -117,8 +117,9 @@ irp_hi    equ 26
 ; later
 ;
 ; assumption:
-; we have never seen MSVC to use anything but eax,ecx, edx
-; so we only protect eax, ebx, ecx, edx to conserve stack space
+; we have never seen MSVC to use anything but eax, ecx, edx,
+; nor have we seen Borland C to use anything but eax, edx,
+; so we only protect eax, ecx, edx to conserve stack space
 ;
 ; to save even more stack space, we save only HIGH part of regs
 ; at some expense of slower execution. it's easier anyway :-)
@@ -148,8 +149,6 @@ irp_hi    equ 26
 	%else
 		push eax
 		pop ax
-		push ebx
-		pop bx
 		push ecx
 		pop cx
 		push edx
@@ -168,8 +167,6 @@ irp_hi    equ 26
 		pop edx
 		push cx
 		pop ecx
-		push bx
-		pop ebx
 		push ax
 		pop eax
 	%endif

kernel/entry.asm

@@ -352,7 +352,7 @@ int21_exit_nodec:
 %ifdef WATCOM
                 sub bp, 4   ; for fs and gs only
 %else        
-		sub bp, 8   ; high parts of eax, ebx, ecx, edx
+		sub bp, 6   ; high parts of eax, ecx, edx
 %endif        
 %endif				
 

kernel/inthndlr.c

@@ -1635,7 +1635,7 @@ struct int2f12regs {
 #ifdef __WATCOMC__
   /* UWORD gs, fs;  ** GS/FS are protected through SI/DI */
 #else
-  UWORD high_edx, high_ecx, high_ebx, high_eax;
+  UWORD high_edx, high_ecx, high_eax;
 #endif
 #endif
   UWORD es, ds;