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-rw-r--r--arch/i386/math-emu/reg_divide.c207
1 files changed, 207 insertions, 0 deletions
diff --git a/arch/i386/math-emu/reg_divide.c b/arch/i386/math-emu/reg_divide.c
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+/*---------------------------------------------------------------------------+
+ | reg_divide.c |
+ | |
+ | Divide one FPU_REG by another and put the result in a destination FPU_REG.|
+ | |
+ | Copyright (C) 1996 |
+ | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
+ | E-mail billm@jacobi.maths.monash.edu.au |
+ | |
+ | Return value is the tag of the answer, or-ed with FPU_Exception if |
+ | one was raised, or -1 on internal error. |
+ | |
+ +---------------------------------------------------------------------------*/
+
+/*---------------------------------------------------------------------------+
+ | The destination may be any FPU_REG, including one of the source FPU_REGs. |
+ +---------------------------------------------------------------------------*/
+
+#include "exception.h"
+#include "reg_constant.h"
+#include "fpu_emu.h"
+#include "fpu_system.h"
+
+/*
+ Divide one register by another and put the result into a third register.
+ */
+int FPU_div(int flags, int rm, int control_w)
+{
+ FPU_REG x, y;
+ FPU_REG const *a, *b, *st0_ptr, *st_ptr;
+ FPU_REG *dest;
+ u_char taga, tagb, signa, signb, sign, saved_sign;
+ int tag, deststnr;
+
+ if ( flags & DEST_RM )
+ deststnr = rm;
+ else
+ deststnr = 0;
+
+ if ( flags & REV )
+ {
+ b = &st(0);
+ st0_ptr = b;
+ tagb = FPU_gettag0();
+ if ( flags & LOADED )
+ {
+ a = (FPU_REG *)rm;
+ taga = flags & 0x0f;
+ }
+ else
+ {
+ a = &st(rm);
+ st_ptr = a;
+ taga = FPU_gettagi(rm);
+ }
+ }
+ else
+ {
+ a = &st(0);
+ st0_ptr = a;
+ taga = FPU_gettag0();
+ if ( flags & LOADED )
+ {
+ b = (FPU_REG *)rm;
+ tagb = flags & 0x0f;
+ }
+ else
+ {
+ b = &st(rm);
+ st_ptr = b;
+ tagb = FPU_gettagi(rm);
+ }
+ }
+
+ signa = getsign(a);
+ signb = getsign(b);
+
+ sign = signa ^ signb;
+
+ dest = &st(deststnr);
+ saved_sign = getsign(dest);
+
+ if ( !(taga | tagb) )
+ {
+ /* Both regs Valid, this should be the most common case. */
+ reg_copy(a, &x);
+ reg_copy(b, &y);
+ setpositive(&x);
+ setpositive(&y);
+ tag = FPU_u_div(&x, &y, dest, control_w, sign);
+
+ if ( tag < 0 )
+ return tag;
+
+ FPU_settagi(deststnr, tag);
+ return tag;
+ }
+
+ if ( taga == TAG_Special )
+ taga = FPU_Special(a);
+ if ( tagb == TAG_Special )
+ tagb = FPU_Special(b);
+
+ if ( ((taga == TAG_Valid) && (tagb == TW_Denormal))
+ || ((taga == TW_Denormal) && (tagb == TAG_Valid))
+ || ((taga == TW_Denormal) && (tagb == TW_Denormal)) )
+ {
+ if ( denormal_operand() < 0 )
+ return FPU_Exception;
+
+ FPU_to_exp16(a, &x);
+ FPU_to_exp16(b, &y);
+ tag = FPU_u_div(&x, &y, dest, control_w, sign);
+ if ( tag < 0 )
+ return tag;
+
+ FPU_settagi(deststnr, tag);
+ return tag;
+ }
+ else if ( (taga <= TW_Denormal) && (tagb <= TW_Denormal) )
+ {
+ if ( tagb != TAG_Zero )
+ {
+ /* Want to find Zero/Valid */
+ if ( tagb == TW_Denormal )
+ {
+ if ( denormal_operand() < 0 )
+ return FPU_Exception;
+ }
+
+ /* The result is zero. */
+ FPU_copy_to_regi(&CONST_Z, TAG_Zero, deststnr);
+ setsign(dest, sign);
+ return TAG_Zero;
+ }
+ /* We have an exception condition, either 0/0 or Valid/Zero. */
+ if ( taga == TAG_Zero )
+ {
+ /* 0/0 */
+ return arith_invalid(deststnr);
+ }
+ /* Valid/Zero */
+ return FPU_divide_by_zero(deststnr, sign);
+ }
+ /* Must have infinities, NaNs, etc */
+ else if ( (taga == TW_NaN) || (tagb == TW_NaN) )
+ {
+ if ( flags & LOADED )
+ return real_2op_NaN((FPU_REG *)rm, flags & 0x0f, 0, st0_ptr);
+
+ if ( flags & DEST_RM )
+ {
+ int tag;
+ tag = FPU_gettag0();
+ if ( tag == TAG_Special )
+ tag = FPU_Special(st0_ptr);
+ return real_2op_NaN(st0_ptr, tag, rm, (flags & REV) ? st0_ptr : &st(rm));
+ }
+ else
+ {
+ int tag;
+ tag = FPU_gettagi(rm);
+ if ( tag == TAG_Special )
+ tag = FPU_Special(&st(rm));
+ return real_2op_NaN(&st(rm), tag, 0, (flags & REV) ? st0_ptr : &st(rm));
+ }
+ }
+ else if (taga == TW_Infinity)
+ {
+ if (tagb == TW_Infinity)
+ {
+ /* infinity/infinity */
+ return arith_invalid(deststnr);
+ }
+ else
+ {
+ /* tagb must be Valid or Zero */
+ if ( (tagb == TW_Denormal) && (denormal_operand() < 0) )
+ return FPU_Exception;
+
+ /* Infinity divided by Zero or Valid does
+ not raise and exception, but returns Infinity */
+ FPU_copy_to_regi(a, TAG_Special, deststnr);
+ setsign(dest, sign);
+ return taga;
+ }
+ }
+ else if (tagb == TW_Infinity)
+ {
+ if ( (taga == TW_Denormal) && (denormal_operand() < 0) )
+ return FPU_Exception;
+
+ /* The result is zero. */
+ FPU_copy_to_regi(&CONST_Z, TAG_Zero, deststnr);
+ setsign(dest, sign);
+ return TAG_Zero;
+ }
+#ifdef PARANOID
+ else
+ {
+ EXCEPTION(EX_INTERNAL|0x102);
+ return FPU_Exception;
+ }
+#endif /* PARANOID */
+
+ return 0;
+}