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New callback type with STI and the idle call steals some cycles to speed things up.

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Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@507
This commit is contained in:
Sjoerd van der Berg 2002-11-17 08:40:43 +00:00
parent 6a16c109af
commit 0dbbf37f95
1 changed files with 13 additions and 3 deletions
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16
src/cpu/callback.cpp
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@ -23,7 +23,7 @@
#include "callback.h"
#include "mem.h"
#include "cpu.h"
#include "pic.h"
/* CallBack are located at 0xC800:0
And they are 16 bytes each and you can define them to behave in certain ways like a
@ -62,6 +62,8 @@ void CALLBACK_Idle(void) {
reg_eip=oldeip;
SegSet16(cs,oldcs);
flags.intf=oldintf;
if (CPU_CycleLeft<300) CPU_CycleLeft=1;
else CPU_CycleLeft-=300;
}
static Bitu default_handler(void) {
@ -119,17 +121,25 @@ bool CALLBACK_Setup(Bitu callback,CallBack_Handler handler,Bitu type) {
if (callback>=CB_MAX) return false;
switch (type) {
case CB_RETF:
real_writeb((Bit16u)CB_SEG,(callback<<4),(Bit8u)0xFE); //GRP 4
real_writeb((Bit16u)CB_SEG,(callback<<4)+0,(Bit8u)0xFE); //GRP 4
real_writeb((Bit16u)CB_SEG,(callback<<4)+1,(Bit8u)0x38); //Extra Callback instruction
real_writew((Bit16u)CB_SEG,(callback<<4)+2,callback); //The immediate word
real_writeb((Bit16u)CB_SEG,(callback<<4)+4,(Bit8u)0xCB); //A RETF Instruction
break;
case CB_IRET:
real_writeb((Bit16u)CB_SEG,(callback<<4),(Bit8u)0xFE); //GRP 4
real_writeb((Bit16u)CB_SEG,(callback<<4)+0,(Bit8u)0xFE); //GRP 4
real_writeb((Bit16u)CB_SEG,(callback<<4)+1,(Bit8u)0x38); //Extra Callback instruction
real_writew((Bit16u)CB_SEG,(callback<<4)+2,callback); //The immediate word
real_writeb((Bit16u)CB_SEG,(callback<<4)+4,(Bit8u)0xCF); //An IRET Instruction
break;
case CB_IRET_STI:
real_writeb((Bit16u)CB_SEG,(callback<<4)+0,(Bit8u)0xFB); //STI
real_writeb((Bit16u)CB_SEG,(callback<<4)+1,(Bit8u)0xFE); //GRP 4
real_writeb((Bit16u)CB_SEG,(callback<<4)+2,(Bit8u)0x38); //Extra Callback instruction
real_writew((Bit16u)CB_SEG,(callback<<4)+3,callback); //The immediate word
real_writeb((Bit16u)CB_SEG,(callback<<4)+5,(Bit8u)0xCF); //An IRET Instruction
break;
default:
E_Exit("CALLBACK:Setup:Illegal type %d",type);