65 lines
1.6 KiB
C
65 lines
1.6 KiB
C
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/*
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SIMULATE.C - Shows how to issue a real-mode interrupt
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from protected mode using DPMI call 300h. Any buffers
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to be passed to DOS must be allocated in DOS memory
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This can be done with DPMI call 100h. This program
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will call DOS int 21, function 39h, "Create
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Directory".
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Compile & Link: wcl386 /l=dos4g simulate
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*/
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#include <i86.h>
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#include <dos.h>
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#include <stdio.h>
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#include <string.h>
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static struct rminfo {
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long EDI;
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long ESI;
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long EBP;
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long reserved_by_system;
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long EBX;
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long EDX;
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long ECX;
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long EAX;
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short flags;
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short ES,DS,FS,GS,IP,CS,SP,SS;
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} RMI;
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void main()
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{
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union REGS regs;
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struct SREGS sregs;
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int interrupt_no=0x31;
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short selector;
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short segment;
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char far *str;
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/* DPMI call 100h allocates DOS memory */
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memset(&sregs,0,sizeof(sregs));
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regs.w.ax=0x0100;
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regs.w.bx=0x0001;
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int386x( interrupt_no, ®s, ®s, &sregs);
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segment=regs.w.ax;
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selector=regs.w.dx;
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/* Move string to DOS real-mode memory */
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str=MK_FP(selector,0);
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_fstrcpy( str, "myjunk" );
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/* Set up real-mode call structure */
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memset(&RMI,0,sizeof(RMI));
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RMI.EAX=0x00003900; /* call service 39h ah=0x39 */
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RMI.DS=segment; /* put DOS seg:off into DS:DX*/
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RMI.EDX=0; /* DOS ignores EDX high word */
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/* Use DMPI call 300h to issue the DOS interrupt */
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regs.w.ax = 0x0300;
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regs.h.bl = 0x21;
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regs.h.bh = 0;
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regs.w.cx = 0;
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sregs.es = FP_SEG(&RMI);
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regs.x.edi = FP_OFF(&RMI);
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int386x( interrupt_no, ®s, ®s, &sregs );
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}
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