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Diffstat (limited to 'arch/i386/math-emu/reg_compare.c')
-rw-r--r--arch/i386/math-emu/reg_compare.c381
1 files changed, 381 insertions, 0 deletions
diff --git a/arch/i386/math-emu/reg_compare.c b/arch/i386/math-emu/reg_compare.c
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index 00000000000..f37c5b5a35a
--- /dev/null
+++ b/arch/i386/math-emu/reg_compare.c
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+/*---------------------------------------------------------------------------+
+ | reg_compare.c |
+ | |
+ | Compare two floating point registers |
+ | |
+ | Copyright (C) 1992,1993,1994,1997 |
+ | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
+ | E-mail billm@suburbia.net |
+ | |
+ | |
+ +---------------------------------------------------------------------------*/
+
+/*---------------------------------------------------------------------------+
+ | compare() is the core FPU_REG comparison function |
+ +---------------------------------------------------------------------------*/
+
+#include "fpu_system.h"
+#include "exception.h"
+#include "fpu_emu.h"
+#include "control_w.h"
+#include "status_w.h"
+
+
+static int compare(FPU_REG const *b, int tagb)
+{
+ int diff, exp0, expb;
+ u_char st0_tag;
+ FPU_REG *st0_ptr;
+ FPU_REG x, y;
+ u_char st0_sign, signb = getsign(b);
+
+ st0_ptr = &st(0);
+ st0_tag = FPU_gettag0();
+ st0_sign = getsign(st0_ptr);
+
+ if ( tagb == TAG_Special )
+ tagb = FPU_Special(b);
+ if ( st0_tag == TAG_Special )
+ st0_tag = FPU_Special(st0_ptr);
+
+ if ( ((st0_tag != TAG_Valid) && (st0_tag != TW_Denormal))
+ || ((tagb != TAG_Valid) && (tagb != TW_Denormal)) )
+ {
+ if ( st0_tag == TAG_Zero )
+ {
+ if ( tagb == TAG_Zero ) return COMP_A_eq_B;
+ if ( tagb == TAG_Valid )
+ return ((signb == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B);
+ if ( tagb == TW_Denormal )
+ return ((signb == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B)
+ | COMP_Denormal;
+ }
+ else if ( tagb == TAG_Zero )
+ {
+ if ( st0_tag == TAG_Valid )
+ return ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B);
+ if ( st0_tag == TW_Denormal )
+ return ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B)
+ | COMP_Denormal;
+ }
+
+ if ( st0_tag == TW_Infinity )
+ {
+ if ( (tagb == TAG_Valid) || (tagb == TAG_Zero) )
+ return ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B);
+ else if ( tagb == TW_Denormal )
+ return ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B)
+ | COMP_Denormal;
+ else if ( tagb == TW_Infinity )
+ {
+ /* The 80486 book says that infinities can be equal! */
+ return (st0_sign == signb) ? COMP_A_eq_B :
+ ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B);
+ }
+ /* Fall through to the NaN code */
+ }
+ else if ( tagb == TW_Infinity )
+ {
+ if ( (st0_tag == TAG_Valid) || (st0_tag == TAG_Zero) )
+ return ((signb == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B);
+ if ( st0_tag == TW_Denormal )
+ return ((signb == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B)
+ | COMP_Denormal;
+ /* Fall through to the NaN code */
+ }
+
+ /* The only possibility now should be that one of the arguments
+ is a NaN */
+ if ( (st0_tag == TW_NaN) || (tagb == TW_NaN) )
+ {
+ int signalling = 0, unsupported = 0;
+ if ( st0_tag == TW_NaN )
+ {
+ signalling = (st0_ptr->sigh & 0xc0000000) == 0x80000000;
+ unsupported = !((exponent(st0_ptr) == EXP_OVER)
+ && (st0_ptr->sigh & 0x80000000));
+ }
+ if ( tagb == TW_NaN )
+ {
+ signalling |= (b->sigh & 0xc0000000) == 0x80000000;
+ unsupported |= !((exponent(b) == EXP_OVER)
+ && (b->sigh & 0x80000000));
+ }
+ if ( signalling || unsupported )
+ return COMP_No_Comp | COMP_SNaN | COMP_NaN;
+ else
+ /* Neither is a signaling NaN */
+ return COMP_No_Comp | COMP_NaN;
+ }
+
+ EXCEPTION(EX_Invalid);
+ }
+
+ if (st0_sign != signb)
+ {
+ return ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B)
+ | ( ((st0_tag == TW_Denormal) || (tagb == TW_Denormal)) ?
+ COMP_Denormal : 0);
+ }
+
+ if ( (st0_tag == TW_Denormal) || (tagb == TW_Denormal) )
+ {
+ FPU_to_exp16(st0_ptr, &x);
+ FPU_to_exp16(b, &y);
+ st0_ptr = &x;
+ b = &y;
+ exp0 = exponent16(st0_ptr);
+ expb = exponent16(b);
+ }
+ else
+ {
+ exp0 = exponent(st0_ptr);
+ expb = exponent(b);
+ }
+
+#ifdef PARANOID
+ if (!(st0_ptr->sigh & 0x80000000)) EXCEPTION(EX_Invalid);
+ if (!(b->sigh & 0x80000000)) EXCEPTION(EX_Invalid);
+#endif /* PARANOID */
+
+ diff = exp0 - expb;
+ if ( diff == 0 )
+ {
+ diff = st0_ptr->sigh - b->sigh; /* Works only if ms bits are
+ identical */
+ if ( diff == 0 )
+ {
+ diff = st0_ptr->sigl > b->sigl;
+ if ( diff == 0 )
+ diff = -(st0_ptr->sigl < b->sigl);
+ }
+ }
+
+ if ( diff > 0 )
+ {
+ return ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B)
+ | ( ((st0_tag == TW_Denormal) || (tagb == TW_Denormal)) ?
+ COMP_Denormal : 0);
+ }
+ if ( diff < 0 )
+ {
+ return ((st0_sign == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B)
+ | ( ((st0_tag == TW_Denormal) || (tagb == TW_Denormal)) ?
+ COMP_Denormal : 0);
+ }
+
+ return COMP_A_eq_B
+ | ( ((st0_tag == TW_Denormal) || (tagb == TW_Denormal)) ?
+ COMP_Denormal : 0);
+
+}
+
+
+/* This function requires that st(0) is not empty */
+int FPU_compare_st_data(FPU_REG const *loaded_data, u_char loaded_tag)
+{
+ int f = 0, c;
+
+ c = compare(loaded_data, loaded_tag);
+
+ if (c & COMP_NaN)
+ {
+ EXCEPTION(EX_Invalid);
+ f = SW_C3 | SW_C2 | SW_C0;
+ }
+ else
+ switch (c & 7)
+ {
+ case COMP_A_lt_B:
+ f = SW_C0;
+ break;
+ case COMP_A_eq_B:
+ f = SW_C3;
+ break;
+ case COMP_A_gt_B:
+ f = 0;
+ break;
+ case COMP_No_Comp:
+ f = SW_C3 | SW_C2 | SW_C0;
+ break;
+#ifdef PARANOID
+ default:
+ EXCEPTION(EX_INTERNAL|0x121);
+ f = SW_C3 | SW_C2 | SW_C0;
+ break;
+#endif /* PARANOID */
+ }
+ setcc(f);
+ if (c & COMP_Denormal)
+ {
+ return denormal_operand() < 0;
+ }
+ return 0;
+}
+
+
+static int compare_st_st(int nr)
+{
+ int f = 0, c;
+ FPU_REG *st_ptr;
+
+ if ( !NOT_EMPTY(0) || !NOT_EMPTY(nr) )
+ {
+ setcc(SW_C3 | SW_C2 | SW_C0);
+ /* Stack fault */
+ EXCEPTION(EX_StackUnder);
+ return !(control_word & CW_Invalid);
+ }
+
+ st_ptr = &st(nr);
+ c = compare(st_ptr, FPU_gettagi(nr));
+ if (c & COMP_NaN)
+ {
+ setcc(SW_C3 | SW_C2 | SW_C0);
+ EXCEPTION(EX_Invalid);
+ return !(control_word & CW_Invalid);
+ }
+ else
+ switch (c & 7)
+ {
+ case COMP_A_lt_B:
+ f = SW_C0;
+ break;
+ case COMP_A_eq_B:
+ f = SW_C3;
+ break;
+ case COMP_A_gt_B:
+ f = 0;
+ break;
+ case COMP_No_Comp:
+ f = SW_C3 | SW_C2 | SW_C0;
+ break;
+#ifdef PARANOID
+ default:
+ EXCEPTION(EX_INTERNAL|0x122);
+ f = SW_C3 | SW_C2 | SW_C0;
+ break;
+#endif /* PARANOID */
+ }
+ setcc(f);
+ if (c & COMP_Denormal)
+ {
+ return denormal_operand() < 0;
+ }
+ return 0;
+}
+
+
+static int compare_u_st_st(int nr)
+{
+ int f = 0, c;
+ FPU_REG *st_ptr;
+
+ if ( !NOT_EMPTY(0) || !NOT_EMPTY(nr) )
+ {
+ setcc(SW_C3 | SW_C2 | SW_C0);
+ /* Stack fault */
+ EXCEPTION(EX_StackUnder);
+ return !(control_word & CW_Invalid);
+ }
+
+ st_ptr = &st(nr);
+ c = compare(st_ptr, FPU_gettagi(nr));
+ if (c & COMP_NaN)
+ {
+ setcc(SW_C3 | SW_C2 | SW_C0);
+ if (c & COMP_SNaN) /* This is the only difference between
+ un-ordered and ordinary comparisons */
+ {
+ EXCEPTION(EX_Invalid);
+ return !(control_word & CW_Invalid);
+ }
+ return 0;
+ }
+ else
+ switch (c & 7)
+ {
+ case COMP_A_lt_B:
+ f = SW_C0;
+ break;
+ case COMP_A_eq_B:
+ f = SW_C3;
+ break;
+ case COMP_A_gt_B:
+ f = 0;
+ break;
+ case COMP_No_Comp:
+ f = SW_C3 | SW_C2 | SW_C0;
+ break;
+#ifdef PARANOID
+ default:
+ EXCEPTION(EX_INTERNAL|0x123);
+ f = SW_C3 | SW_C2 | SW_C0;
+ break;
+#endif /* PARANOID */
+ }
+ setcc(f);
+ if (c & COMP_Denormal)
+ {
+ return denormal_operand() < 0;
+ }
+ return 0;
+}
+
+/*---------------------------------------------------------------------------*/
+
+void fcom_st(void)
+{
+ /* fcom st(i) */
+ compare_st_st(FPU_rm);
+}
+
+
+void fcompst(void)
+{
+ /* fcomp st(i) */
+ if ( !compare_st_st(FPU_rm) )
+ FPU_pop();
+}
+
+
+void fcompp(void)
+{
+ /* fcompp */
+ if (FPU_rm != 1)
+ {
+ FPU_illegal();
+ return;
+ }
+ if ( !compare_st_st(1) )
+ poppop();
+}
+
+
+void fucom_(void)
+{
+ /* fucom st(i) */
+ compare_u_st_st(FPU_rm);
+
+}
+
+
+void fucomp(void)
+{
+ /* fucomp st(i) */
+ if ( !compare_u_st_st(FPU_rm) )
+ FPU_pop();
+}
+
+
+void fucompp(void)
+{
+ /* fucompp */
+ if (FPU_rm == 1)
+ {
+ if ( !compare_u_st_st(1) )
+ poppop();
+ }
+ else
+ FPU_illegal();
+}