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add small free MCB to start of dos memory (fixes Cannon Fodder2 sound, Xenobots)

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Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@2414
This commit is contained in:
Sebastian Strohhäcker 2005-12-16 21:05:46 +00:00
parent d817b8df8c
commit b9bba72519
1 changed files with 26 additions and 11 deletions
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37
src/dos/dos_memory.cpp
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@ -405,13 +405,6 @@ static Bitu DOS_default_handler(void) {
static CALLBACK_HandlerObject callbackhandler;
void DOS_SetupMemory(void) {
// Create a dummy device MCB with PSPSeg=0x0008
DOS_MCB mcb_devicedummy((Bit16u)DOS_MEM_START);
mcb_devicedummy.SetPSPSeg(MCB_DOS); // Devices
mcb_devicedummy.SetSize(1);
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) */
@ -428,13 +421,35 @@ void DOS_SetupMemory(void) {
real_writed(0,0x04*4,0x700000); //Shadow President
// real_writed(0,0x0f*4,0x700000); //Always a tricky one (soundblaster irq)
DOS_MCB mcb((Bit16u)DOS_MEM_START+2);
// Create a dummy device MCB with PSPSeg=0x0008
DOS_MCB mcb_devicedummy((Bit16u)DOS_MEM_START);
mcb_devicedummy.SetPSPSeg(MCB_DOS); // Devices
mcb_devicedummy.SetSize(1);
mcb_devicedummy.SetType(0x4d); // More blocks will follow
// mcb_devicedummy.SetFileName("SD ");
Bit16u mcb_sizes=2;
// Create a small empty MCB (result from a growing environment block)
DOS_MCB tempmcb((Bit16u)DOS_MEM_START+mcb_sizes);
tempmcb.SetPSPSeg(MCB_FREE);
tempmcb.SetSize(4);
mcb_sizes+=5;
tempmcb.SetType(0x4d);
// Lock the previous empty MCB
DOS_MCB tempmcb2((Bit16u)DOS_MEM_START+mcb_sizes);
tempmcb2.SetPSPSeg(0x40); // can be removed by loadfix
tempmcb2.SetSize(16);
mcb_sizes+=17;
tempmcb2.SetType(0x4d);
DOS_MCB mcb((Bit16u)DOS_MEM_START+mcb_sizes);
mcb.SetPSPSeg(MCB_FREE); //Free
mcb.SetType(0x5a); //Last Block
if (machine==MCH_TANDY) {
/* memory up to 608k available, the rest (to 640k) is used by
the tandy graphics system's variable mapping of 0xb800 */
mcb.SetSize(0x97FE - DOS_MEM_START - 2);
mcb.SetSize(0x97FE - DOS_MEM_START - mcb_sizes);
} else if (machine==MCH_PCJR) {
/* memory from 128k to 640k is available */
mcb_devicedummy.SetPt((Bit16u)0x2000);
@ -449,11 +464,11 @@ void DOS_SetupMemory(void) {
mcb_devicedummy.SetType(0x4d);
/* memory below 96k */
mcb.SetSize(0x1800 - DOS_MEM_START - 4);
mcb.SetSize(0x1800 - DOS_MEM_START - (2+mcb_sizes));
mcb.SetType(0x4d);
} else {
/* complete memory up to 640k available */
mcb.SetSize(0x9FFE - DOS_MEM_START - 2);
mcb.SetSize(0x9FFE - DOS_MEM_START - mcb_sizes);
}
dos.firstMCB=DOS_MEM_START;