380 lines
7.9 KiB
C
380 lines
7.9 KiB
C
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/*---------------------------------------------------------------------------+
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| reg_compare.c |
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| Compare two floating point registers |
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| Copyright (C) 1992,1993,1994 |
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| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
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| Australia. E-mail billm@vaxc.cc.monash.edu.au |
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+---------------------------------------------------------------------------*/
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/*---------------------------------------------------------------------------+
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| compare() is the core FPU_REG comparison function |
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+---------------------------------------------------------------------------*/
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#include "fpu_system.h"
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#include "exception.h"
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#include "fpu_emu.h"
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#include "control_w.h"
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#include "status_w.h"
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int compare(FPU_REG const *b)
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{
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int diff;
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if ( FPU_st0_ptr->tag | b->tag )
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{
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if ( FPU_st0_ptr->tag == TW_Zero )
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{
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if ( b->tag == TW_Zero ) return COMP_A_eq_B;
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if ( b->tag == TW_Valid )
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{
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return ((b->sign == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B)
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#ifdef DENORM_OPERAND
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| ((b->exp <= EXP_UNDER) ?
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COMP_Denormal : 0)
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#endif DENORM_OPERAND
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;
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}
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}
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else if ( b->tag == TW_Zero )
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{
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if ( FPU_st0_ptr->tag == TW_Valid )
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{
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return ((FPU_st0_ptr->sign == SIGN_POS) ? COMP_A_gt_B
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: COMP_A_lt_B)
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#ifdef DENORM_OPERAND
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| ((FPU_st0_ptr->exp <= EXP_UNDER )
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? COMP_Denormal : 0 )
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#endif DENORM_OPERAND
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;
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}
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}
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if ( FPU_st0_ptr->tag == TW_Infinity )
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{
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if ( (b->tag == TW_Valid) || (b->tag == TW_Zero) )
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{
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return ((FPU_st0_ptr->sign == SIGN_POS) ? COMP_A_gt_B
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: COMP_A_lt_B)
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#ifdef DENORM_OPERAND
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| (((b->tag == TW_Valid) && (b->exp <= EXP_UNDER)) ?
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COMP_Denormal : 0 )
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#endif DENORM_OPERAND
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;
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}
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else if ( b->tag == TW_Infinity )
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{
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/* The 80486 book says that infinities can be equal! */
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return (FPU_st0_ptr->sign == b->sign) ? COMP_A_eq_B :
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((FPU_st0_ptr->sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B);
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}
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/* Fall through to the NaN code */
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}
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else if ( b->tag == TW_Infinity )
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{
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if ( (FPU_st0_ptr->tag == TW_Valid) || (FPU_st0_ptr->tag == TW_Zero) )
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{
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return ((b->sign == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B)
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#ifdef DENORM_OPERAND
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| (((FPU_st0_ptr->tag == TW_Valid)
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&& (FPU_st0_ptr->exp <= EXP_UNDER)) ?
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COMP_Denormal : 0)
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#endif DENORM_OPERAND
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;
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}
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/* Fall through to the NaN code */
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}
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/* The only possibility now should be that one of the arguments
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is a NaN */
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if ( (FPU_st0_ptr->tag == TW_NaN) || (b->tag == TW_NaN) )
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{
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if ( ((FPU_st0_ptr->tag == TW_NaN) && !(FPU_st0_ptr->sigh & 0x40000000))
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|| ((b->tag == TW_NaN) && !(b->sigh & 0x40000000)) )
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/* At least one arg is a signaling NaN */
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return COMP_No_Comp | COMP_SNaN | COMP_NaN;
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else
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/* Neither is a signaling NaN */
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return COMP_No_Comp | COMP_NaN;
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}
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EXCEPTION(EX_Invalid);
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}
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#ifdef PARANOID
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if (!(FPU_st0_ptr->sigh & 0x80000000)) EXCEPTION(EX_Invalid);
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if (!(b->sigh & 0x80000000)) EXCEPTION(EX_Invalid);
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#endif PARANOID
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if (FPU_st0_ptr->sign != b->sign)
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{
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return ((FPU_st0_ptr->sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B)
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#ifdef DENORM_OPERAND
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( ((FPU_st0_ptr->exp <= EXP_UNDER) || (b->exp <= EXP_UNDER)) ?
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COMP_Denormal : 0)
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#endif DENORM_OPERAND
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;
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}
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diff = FPU_st0_ptr->exp - b->exp;
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if ( diff == 0 )
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{
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diff = FPU_st0_ptr->sigh - b->sigh; /* Works only if ms bits are
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identical */
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if ( diff == 0 )
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{
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diff = FPU_st0_ptr->sigl > b->sigl;
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if ( diff == 0 )
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diff = -(FPU_st0_ptr->sigl < b->sigl);
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}
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}
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if ( diff > 0 )
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{
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return ((FPU_st0_ptr->sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B)
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#ifdef DENORM_OPERAND
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( ((FPU_st0_ptr->exp <= EXP_UNDER) || (b->exp <= EXP_UNDER)) ?
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COMP_Denormal : 0)
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#endif DENORM_OPERAND
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;
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}
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if ( diff < 0 )
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{
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return ((FPU_st0_ptr->sign == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B)
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#ifdef DENORM_OPERAND
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( ((FPU_st0_ptr->exp <= EXP_UNDER) || (b->exp <= EXP_UNDER)) ?
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COMP_Denormal : 0)
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#endif DENORM_OPERAND
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;
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}
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return COMP_A_eq_B
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#ifdef DENORM_OPERAND
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( ((FPU_st0_ptr->exp <= EXP_UNDER) || (b->exp <= EXP_UNDER)) ?
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COMP_Denormal : 0)
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#endif DENORM_OPERAND
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;
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}
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/* This function requires that st(0) is not empty */
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int compare_st_data(void)
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{
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int f, c;
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c = compare(&FPU_loaded_data);
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if (c & COMP_NaN)
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{
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EXCEPTION(EX_Invalid);
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f = SW_C3 | SW_C2 | SW_C0;
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}
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else
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switch (c & 7)
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{
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case COMP_A_lt_B:
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f = SW_C0;
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break;
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case COMP_A_eq_B:
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f = SW_C3;
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break;
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case COMP_A_gt_B:
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f = 0;
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break;
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case COMP_No_Comp:
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f = SW_C3 | SW_C2 | SW_C0;
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break;
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#ifdef PARANOID
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default:
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EXCEPTION(EX_INTERNAL|0x121);
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f = SW_C3 | SW_C2 | SW_C0;
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break;
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#endif PARANOID
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}
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setcc(f);
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if (c & COMP_Denormal)
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{
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return denormal_operand();
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}
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return 0;
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}
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static int compare_st_st(int nr)
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{
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int f, c;
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if ( !NOT_EMPTY_0 || !NOT_EMPTY(nr) )
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{
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setcc(SW_C3 | SW_C2 | SW_C0);
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/* Stack fault */
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EXCEPTION(EX_StackUnder);
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return !(control_word & CW_Invalid);
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}
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c = compare(&st(nr));
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if (c & COMP_NaN)
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{
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setcc(SW_C3 | SW_C2 | SW_C0);
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EXCEPTION(EX_Invalid);
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return !(control_word & CW_Invalid);
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}
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else
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switch (c & 7)
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{
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case COMP_A_lt_B:
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f = SW_C0;
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break;
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case COMP_A_eq_B:
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f = SW_C3;
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break;
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case COMP_A_gt_B:
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f = 0;
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break;
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case COMP_No_Comp:
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f = SW_C3 | SW_C2 | SW_C0;
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break;
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#ifdef PARANOID
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default:
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EXCEPTION(EX_INTERNAL|0x122);
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f = SW_C3 | SW_C2 | SW_C0;
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break;
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#endif PARANOID
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}
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setcc(f);
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if (c & COMP_Denormal)
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{
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return denormal_operand();
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}
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return 0;
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}
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static int compare_u_st_st(int nr)
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{
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int f, c;
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if ( !NOT_EMPTY_0 || !NOT_EMPTY(nr) )
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{
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setcc(SW_C3 | SW_C2 | SW_C0);
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/* Stack fault */
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EXCEPTION(EX_StackUnder);
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return !(control_word & CW_Invalid);
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}
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c = compare(&st(nr));
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if (c & COMP_NaN)
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{
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setcc(SW_C3 | SW_C2 | SW_C0);
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if (c & COMP_SNaN) /* This is the only difference between
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un-ordered and ordinary comparisons */
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{
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EXCEPTION(EX_Invalid);
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return !(control_word & CW_Invalid);
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}
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return 0;
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}
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else
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switch (c & 7)
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{
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case COMP_A_lt_B:
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f = SW_C0;
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break;
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case COMP_A_eq_B:
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f = SW_C3;
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break;
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case COMP_A_gt_B:
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f = 0;
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break;
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case COMP_No_Comp:
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f = SW_C3 | SW_C2 | SW_C0;
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break;
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#ifdef PARANOID
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default:
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EXCEPTION(EX_INTERNAL|0x123);
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f = SW_C3 | SW_C2 | SW_C0;
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break;
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#endif PARANOID
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}
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setcc(f);
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if (c & COMP_Denormal)
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{
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return denormal_operand();
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}
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return 0;
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}
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/*---------------------------------------------------------------------------*/
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void fcom_st()
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{
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/* fcom st(i) */
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compare_st_st(FPU_rm);
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}
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void fcompst()
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{
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/* fcomp st(i) */
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if ( !compare_st_st(FPU_rm) )
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pop();
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}
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void fcompp()
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{
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/* fcompp */
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if (FPU_rm != 1)
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{
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FPU_illegal();
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return;
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}
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if ( !compare_st_st(1) )
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{
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pop(); FPU_st0_ptr = &st(0);
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pop();
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}
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}
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void fucom_()
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{
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/* fucom st(i) */
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compare_u_st_st(FPU_rm);
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}
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void fucomp()
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{
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/* fucomp st(i) */
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if ( !compare_u_st_st(FPU_rm) )
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pop();
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}
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void fucompp()
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{
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/* fucompp */
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if (FPU_rm == 1)
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{
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if ( !compare_u_st_st(1) )
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{
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pop(); FPU_st0_ptr = &st(0);
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pop();
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}
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}
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else
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FPU_illegal();
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}
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