MSDOS Error Table Handling

[ccrayne at crayne.org]

The following patch is my first submission to this list, so please let me
know if I should be doing something differently.

-- Chuck Crayne
-----------------------------------------------------------
ccrayne at crayne.org
-----------------------------------------------------------
Change Log:
include/miscemu.h, msdos/dosmem.c, msdos/int2f.c
ccrayne at crayne.org
Fix Error Table handling to eliminate "No real-mode handler for errors
yet!" fixme, and associated SIGILL abort.

--- include/miscemu.h.20011226	Wed Jan  2 18:05:36 2002
+++ include/miscemu.h	Wed Jan  2 21:40:13 2002
@@ -152,6 +152,10 @@
 extern LPVOID DOSMEM_MapDosToLinear(UINT); /* linear DOS to Wine */
 extern UINT DOSMEM_MapLinearToDos(LPVOID); /* linear Wine to DOS */
 
+/* DOS Error Table addresses */
+extern DWORD DOSMEM_ErrorCall;
+extern DWORD DOSMEM_ErrorBuffer;
+
 /* memory/instr.c */
 extern BOOL INSTR_EmulateInstruction( CONTEXT86 *context );
 
--- msdos/dosmem.c.20011226	Wed Jan  2 17:27:40 2002
+++ msdos/dosmem.c	Thu Jan  3 11:08:26 2002
@@ -32,6 +32,8 @@
 WORD DOSMEM_BiosSysSeg;   /* BIOS ROM segment at 0xf000:0 */
 
 DWORD DOSMEM_CollateTable;
+DWORD DOSMEM_ErrorCall;
+DWORD DOSMEM_ErrorBuffer;
 
 /* use 2 low bits of 'size' for the housekeeping */
 
@@ -359,52 +361,51 @@
  */
 static void DOSMEM_InitErrorTable()
 {
-#if 0  /* no longer used */
 	DWORD		x;
 	char 		*call;
 
-        /* We will use a snippet of real mode code that calls */ +       
/* We use a snippet of real mode code that calls */
         /* a WINE-only interrupt to handle moving the requested */ -       
/* message into the buffer... */
+        /* message into the buffer... 
 
-        /* FIXME - There is still something wrong... */
-
-        /* FIXME - Find hex values for opcodes...
            
            (On call, AX contains message number
-                     DI contains 'offset' (??)
-            Resturn, ES:DI points to counted string )
+                     DI contains table number
+            Return, ES:DI points to counted string )
 
+           PUSH AX
            PUSH BX
+           PUSH DX
            MOV BX, AX
-           MOV AX, (arbitrary subfunction number)
-           INT (WINE-only interrupt)
+           MOV AX, 122eh ;Get or Set Table Address
+           MOV DX, 007fh ;Wine helper function
+           INT 2fh       ;Multiplex interupt
+           POP DX
            POP BX
-           RET
+           POP AX
+           RETF
 
         */
            
-        const int	code = 4;	
-        const int	buffer = 80; 
-        const int 	SIZE_TO_ALLOCATE = code + buffer;
-
-        /* FIXME - Complete rewrite of the table system to save */ -       
/* precious DOS space. Now, we return the 0001:???? as */ -        /* DOS
4+ (??, it seems to be the case in MS 7.10) treats that */ -        /* as
a special case and programs will use the alternate */ -        /*
interface (a farcall returned with INT 24 (AX = 0x122e, DL = */ -       
/* 0x08) which lets us have a smaller memory footprint anyway. */ - 
- 	x = GlobalDOSAlloc16(SIZE_TO_ALLOCATE);  
+        const int	codesz = 32; /* For alignment - current code 1s 17
bytes */	 +        const int	buffersz = 80; /* Just a guess */
+        const int 	SIZE_TO_ALLOCATE = codesz + buffersz;
+        const char  *code =
"\x50\x53\x52\x89\xc3\xb8\x2e\x12\xba\x7f\x00\xcd\x2f\x5a\x5b\x58\xcB"; +
+        /* LOGIC - The "Get Table Address" subfunctions of Int2f AX =
0x122e +           return 1 as the segment address, and error table number
as the offset, +           which tells the caller to invoke the above
routine to find the +           desired error message.
+        */
 
+ 	x = GlobalDOSAlloc16(SIZE_TO_ALLOCATE);  
 	DOSMEM_ErrorCall = MAKELONG(0,(x>>16));
-        DOSMEM_ErrorBuffer = DOSMEM_ErrorCall + code;
+        DOSMEM_ErrorBuffer = DOSMEM_ErrorCall + codesz;
 
 	call = DOSMEM_MapRealToLinear(DOSMEM_ErrorCall);
 
         memset(call, 0, SIZE_TO_ALLOCATE);
-#endif
-        /* Fixme - Copy assembly into buffer here */         +       
memcpy(call,code,17);
 }
 
 /***********************************************************************
--- msdos/int2f.c.20011226	Wed Jan  2 18:04:33 2002
+++ msdos/int2f.c	Thu Jan  3 10:50:46 2002
@@ -61,6 +61,7 @@
         case 0x2e: /* get or set DOS error table address */
             switch (DL_reg(context))
             {
+            char *buff;
             /* Four tables: even commands are 'get', odd are 'set' */
             /* DOS 5.0+ ignores "set" commands */
             case 0x01:
@@ -77,10 +78,19 @@
             case 0x04:
             case 0x06: 
                 context->SegEs = 0x0001;
-                DI_reg(context) = 0x0000;
+                DI_reg(context) = DL_reg(context)>>1;
                 break;
+            /* Return address of error message retriever */
             case 0x08:
-                FIXME("No real-mode handler for errors yet! (bye!)\n"); +               
context->SegEs = DOSMEM_ErrorCall >> 16;
+                DI_reg(context) = DOSMEM_ErrorCall & 0xffff; +               
break;
+            /* Return address of error message counted string */ +           
case 0x7f:
+	        buff = DOSMEM_MapRealToLinear(DOSMEM_ErrorBuffer);
+                sprintf(buff,"\x18""Error %3d from table
%1d\n",BX_reg(context),DI_reg(context));  +                context->SegEs
= DOSMEM_ErrorBuffer >> 16;
+                DI_reg(context) = DOSMEM_ErrorBuffer & 0xffff;
                 break;
             default:
                 INT_BARF(context, 0x2f);