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EXEC improvements, mostly for the load-but-do-not-execute function.

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Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@3978
This commit is contained in:
ripsaw8080 2016-04-05 05:44:43 +00:00
parent f0cf2bc6b0
commit 3c95f17d95
1 changed files with 47 additions and 45 deletions
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92
src/dos/dos_execute.cpp
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@ -427,26 +427,7 @@ bool DOS_Execute(char * name,PhysPt block_pt,Bit8u flags) {
if (head.initSP<4) LOG(LOG_EXEC,LOG_ERROR)("stack underflow/wrap at EXEC");
}
if (flags==LOAD) {
SaveRegisters();
DOS_PSP callpsp(dos.psp());
/* Save the SS:SP on the PSP of calling program */
callpsp.SetStack(RealMakeSeg(ss,reg_sp));
reg_sp+=18;
/* Switch the psp's */
dos.psp(pspseg);
DOS_PSP newpsp(dos.psp());
dos.dta(RealMake(newpsp.GetSegment(),0x80));
/* First word on the stack is the value ax should contain on startup */
real_writew(RealSeg(sssp-2),RealOff(sssp-2),0xffff);
block.exec.initsssp = sssp-2;
block.exec.initcsip = csip;
block.SaveData();
return true;
}
if (flags==LOADNGO) {
if ((reg_sp>0xfffe) || (reg_sp<18)) LOG(LOG_EXEC,LOG_ERROR)("stack underflow/wrap at EXEC");
if ((flags==LOAD) || (flags==LOADNGO)) {
/* Get Caller's program CS:IP of the stack and set termination address to that */
RealSetVec(0x22,RealMake(mem_readw(SegPhys(ss)+reg_sp+2),mem_readw(SegPhys(ss)+reg_sp)));
SaveRegisters();
@ -462,39 +443,18 @@ bool DOS_Execute(char * name,PhysPt block_pt,Bit8u flags) {
/* copy fcbs */
newpsp.SetFCB1(block.exec.fcb1);
newpsp.SetFCB2(block.exec.fcb2);
/* Save the SS:SP on the PSP of new program */
newpsp.SetStack(RealMakeSeg(ss,reg_sp));
/* Setup ax and bx, they contain a 0xff in al and ah if the drive in the fcb is not valid */
/* Setup bx, contains a 0xff in bl and bh if the drive in the fcb is not valid */
DOS_FCB fcb1(RealSeg(block.exec.fcb1),RealOff(block.exec.fcb1));
DOS_FCB fcb2(RealSeg(block.exec.fcb2),RealOff(block.exec.fcb2));
Bit8u d1 = fcb1.GetDrive(); //depends on 0 giving the dos.default drive
if ( (d1>=DOS_DRIVES) || !Drives[d1] ) reg_bl = 0xFF; else reg_bl = 0;
Bit8u d2 = fcb2.GetDrive();
if ( (d2>=DOS_DRIVES) || !Drives[d2] ) reg_bh = 0xFF; else reg_bh = 0;
reg_ax = reg_bx;
/* Set the stack for new program */
SegSet16(ss,RealSeg(sssp));reg_sp=RealOff(sssp);
/* Add some flags and CS:IP on the stack for the IRET */
CPU_Push16(RealSeg(csip));
CPU_Push16(RealOff(csip));
/* DOS starts programs with a RETF, so critical flags
* should not be modified (IOPL in v86 mode);
* interrupt flag is set explicitly, test flags cleared */
reg_flags=(reg_flags&(~FMASK_TEST))|FLAG_IF;
//Jump to retf so that we only need to store cs:ip on the stack
reg_ip++;
/* Setup the rest of the registers */
reg_cx=0xff;
reg_dx=pspseg;
reg_si=RealOff(csip);
reg_di=RealOff(sssp);
reg_bp=0x91c; /* DOS internal stack begin relict */
SegSet16(ds,pspseg);SegSet16(es,pspseg);
#if C_DEBUG
/* Started from debug.com, then set breakpoint at start */
DEBUG_CheckExecuteBreakpoint(RealSeg(csip),RealOff(csip));
#endif
/* Add the filename to PSP and environment MCB's */
/* Write filename in new program MCB */
char stripname[8]= { 0 };Bitu index=0;
while (char chr=*name++) {
switch (chr) {
@ -512,6 +472,48 @@ bool DOS_Execute(char * name,PhysPt block_pt,Bit8u flags) {
DOS_MCB pspmcb(dos.psp()-1);
pspmcb.SetFileName(stripname);
DOS_UpdatePSPName();
}
if (flags==LOAD) {
/* First word on the stack is the value ax should contain on startup */
real_writew(RealSeg(sssp-2),RealOff(sssp-2),reg_bx);
/* Write initial CS:IP and SS:SP in param block */
block.exec.initsssp = sssp-2;
block.exec.initcsip = csip;
block.SaveData();
/* Changed registers */
reg_sp+=18;
reg_ax=RealOff(csip);
reg_bx=memsize;
reg_dx=0;
return true;
}
if (flags==LOADNGO) {
if ((reg_sp>0xfffe) || (reg_sp<18)) LOG(LOG_EXEC,LOG_ERROR)("stack underflow/wrap at EXEC");
/* Set the stack for new program */
SegSet16(ss,RealSeg(sssp));reg_sp=RealOff(sssp);
/* Add some flags and CS:IP on the stack for the IRET */
CPU_Push16(RealSeg(csip));
CPU_Push16(RealOff(csip));
/* DOS starts programs with a RETF, so critical flags
* should not be modified (IOPL in v86 mode);
* interrupt flag is set explicitly, test flags cleared */
reg_flags=(reg_flags&(~FMASK_TEST))|FLAG_IF;
//Jump to retf so that we only need to store cs:ip on the stack
reg_ip++;
/* Setup the rest of the registers */
reg_ax=reg_bx;
reg_cx=0xff;
reg_dx=pspseg;
reg_si=RealOff(csip);
reg_di=RealOff(sssp);
reg_bp=0x91c; /* DOS internal stack begin relict */
SegSet16(ds,pspseg);SegSet16(es,pspseg);
#if C_DEBUG
/* Started from debug.com, then set breakpoint at start */
DEBUG_CheckExecuteBreakpoint(RealSeg(csip),RealOff(csip));
#endif
return true;
}
return false;