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Let dos allocate/hook a few bios interrupts. Makes some buggy game (Shadow President) happy. (thanks to wd to debug this)

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Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@2305
This commit is contained in:
Peter Veenstra 2005-09-08 13:11:35 +00:00
parent d8d805b2ce
commit b6fbe42e85
1 changed files with 21 additions and 0 deletions
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21
src/dos/dos_memory.cpp
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@ -19,6 +19,7 @@
#include "dosbox.h"
#include "mem.h"
#include "dos_inc.h"
#include "callback.h"
#define UMB_START_SEG 0x9fff
@ -343,6 +344,12 @@ bool DOS_LinkUMBsToMemChain(Bit16u linkstate) {
}
static Bitu DOS_default_handler(void) {
LOG(LOG_CPU,LOG_ERROR)("DOS rerouted Interrupt Called %X",lastint);
return CBRET_NONE;
};
static CALLBACK_HandlerObject callbackhandler;
void DOS_SetupMemory(void) {
// Create a dummy device MCB with PSPSeg=0x0008
DOS_MCB mcb_devicedummy((Bit16u)DOS_MEM_START);
@ -351,9 +358,23 @@ void DOS_SetupMemory(void) {
mcb_devicedummy.SetType(0x4d); // More blocks will follow
// mcb_devicedummy.SetFileName("SD ");
/* Let dos claim a few bios interrupts. Makes DOSBox more compatible with
* buggy games, which compare against the interrupt table. (probably a
* broken linked list implementation) */
// BioMenace (segment of int2<0x8000)
mem_writeb((DOS_MEM_START+1)<<4,0xcf);// iret
RealSetVec(0x02,(DOS_MEM_START+1)<<16);
callbackhandler.Allocate(&DOS_default_handler,"DOS default int");
//Shadow president wants int 4 to point to this.
real_writeb(0x70,0,(Bit8u)0xFE); //GRP 4
real_writeb(0x70,1,(Bit8u)0x38); //Extra Callback instruction
real_writew(0x70,2,callbackhandler.Get_callback()); //The immediate word
real_writeb(0x70,4,(Bit8u)0xCF); //An IRET Instruction
real_writed(0,0x04*4,0x700000);
//claim some more ints to this location
real_writed(0,0x01*4,0x700000);
real_writed(0,0x03*4,0x700000);
// real_writed(0,0x0f*4,0x700000); //Always a tricky one (soundblaster irq)
DOS_MCB mcb((Bit16u)DOS_MEM_START+2);
mcb.SetPSPSeg(MCB_FREE); //Free