+++ /dev/null
-/*---------------------------------------------------------------------------+
- | 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();
-}
git.openpandora.org / pandora-kernel.git / blobdiff