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basic FXTRACT support

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Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@2021
This commit is contained in:
Peter Veenstra 2004-10-12 16:19:45 +00:00
parent 93a8163a4d
commit b00484d130
2 changed files with 16 additions and 2 deletions
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5
src/fpu/fpu.cpp
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@ -16,7 +16,7 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
/* $Id: fpu.cpp,v 1.22 2004-09-08 08:46:37 qbix79 Exp $ */
/* $Id: fpu.cpp,v 1.23 2004-10-12 16:19:45 qbix79 Exp $ */
#include "dosbox.h"
#if C_FPU
@ -354,6 +354,9 @@ void FPU_ESC1_Normal(Bitu rm) {
case 0x03: /* FPATAN */
FPU_FPATAN();
break;
case 0x04: /* FXTRACT */
FPU_FXTRACT();
break;
default:
LOG(LOG_FPU,LOG_WARN)("ESC 1:Unhandled group %X subfunction %X",group,sub);
break;

13
src/fpu/fpu_instructions.h
View file

@ -16,7 +16,7 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
/* $Id: fpu_instructions.h,v 1.21 2004-09-09 18:36:50 qbix79 Exp $ */
/* $Id: fpu_instructions.h,v 1.22 2004-10-12 16:19:45 qbix79 Exp $ */
static void FPU_FINIT(void) {
@ -392,3 +392,14 @@ static void FPU_FSTOR(PhysPt addr){
}
}
static void FPU_FXTRACT(void) {
// function stores real bias in st and
// pushes the significant number onto the stack
// if double ever uses a different base please correct this function
FPU_Reg test = fpu.regs[TOP];
Bit64s exp80 = test.ll&LONGTYPE(0x7ff0000000000000);
Bit64s exp80final = (exp80>>52) - BIAS64;
Real64 mant = test.d / (pow(2.0,static_cast<Real64>(exp80final)));
FPU_PUSH(mant);
}