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https://git.hardenedbsd.org/hardenedbsd/HardenedBSD.git
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372 lines
8.9 KiB
C
372 lines
8.9 KiB
C
/*
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* reg_compare.c
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*
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* Compare two floating point registers
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*
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*
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* Copyright (C) 1992, 1993 W. Metzenthen, 22 Parker St, Ormond,
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* Vic 3163, Australia.
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* E-mail apm233m@vaxc.cc.monash.edu.au
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* All rights reserved.
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*
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* This copyright notice covers the redistribution and use of the
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* FPU emulator developed by W. Metzenthen. It covers only its use
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* in the 386BSD operating system. Any other use is not permitted
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* under this copyright.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must include information specifying
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* that source code for the emulator is freely available and include
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* either:
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* a) an offer to provide the source code for a nominal distribution
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* fee, or
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* b) list at least two alternative methods whereby the source
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* can be obtained, e.g. a publically accessible bulletin board
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* and an anonymous ftp site from which the software can be
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* downloaded.
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* 3. All advertising materials specifically mentioning features or use of
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* this emulator must acknowledge that it was developed by W. Metzenthen.
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* 4. The name of W. Metzenthen may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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* W. METZENTHEN BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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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 "param.h"
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#include "proc.h"
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#include "systm.h"
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#include "machine/cpu.h"
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#include "machine/pcb.h"
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#include "fpu_emu.h"
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#include "fpu_system.h"
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#include "exception.h"
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#include "control_w.h"
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#include "status_w.h"
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int
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compare(FPU_REG * 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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if (FPU_st0_ptr->tag == TW_Zero) {
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if (b->tag == TW_Zero)
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return COMP_A_eq_B;
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if (b->tag == TW_Valid) {
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#ifdef DENORM_OPERAND
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if ((b->exp <= EXP_UNDER) && (denormal_operand()))
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return COMP_Denormal;
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#endif /* DENORM_OPERAND */
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return (b->sign == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B;
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}
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} else
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if (b->tag == TW_Zero) {
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if (FPU_st0_ptr->tag == TW_Valid) {
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#ifdef DENORM_OPERAND
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if ((FPU_st0_ptr->exp <= EXP_UNDER) && (denormal_operand()))
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return COMP_Denormal;
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#endif /* DENORM_OPERAND */
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return (FPU_st0_ptr->sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B;
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}
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}
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if (FPU_st0_ptr->tag == TW_Infinity) {
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if ((b->tag == TW_Valid) || (b->tag == TW_Zero)) {
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#ifdef DENORM_OPERAND
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if ((b->tag == TW_Valid) && (b->exp <= EXP_UNDER)
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&& (denormal_operand()))
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return COMP_Denormal;
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#endif /* DENORM_OPERAND */
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return (FPU_st0_ptr->sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B;
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} else
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if (b->tag == TW_Infinity) {
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/* The 80486 book says that infinities
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* 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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} else
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if (b->tag == TW_Infinity) {
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if ((FPU_st0_ptr->tag == TW_Valid) || (FPU_st0_ptr->tag == TW_Zero)) {
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#ifdef DENORM_OPERAND
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if ((FPU_st0_ptr->tag == TW_Valid)
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&& (FPU_st0_ptr->exp <= EXP_UNDER)
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&& (denormal_operand()))
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return COMP_Denormal;
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#endif /* DENORM_OPERAND */
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return (b->sign == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B;
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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
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* arguments is a NaN */
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if ((FPU_st0_ptr->tag == TW_NaN) || (b->tag == TW_NaN)) {
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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))
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EXCEPTION(EX_Invalid);
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if (!(b->sigh & 0x80000000))
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EXCEPTION(EX_Invalid);
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#endif /* PARANOID */
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#ifdef DENORM_OPERAND
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if (((FPU_st0_ptr->exp <= EXP_UNDER) ||
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(b->exp <= EXP_UNDER)) && (denormal_operand()))
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return COMP_Denormal;
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#endif /* DENORM_OPERAND */
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if (FPU_st0_ptr->sign != b->sign)
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return (FPU_st0_ptr->sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B;
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diff = FPU_st0_ptr->exp - b->exp;
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if (diff == 0) {
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diff = FPU_st0_ptr->sigh - b->sigh; /* Works only if ms bits
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* are identical */
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if (diff == 0) {
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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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return (FPU_st0_ptr->sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B;
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if (diff < 0)
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return (FPU_st0_ptr->sign == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B;
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return COMP_A_eq_B;
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}
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/* This function requires that st(0) is not empty */
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int
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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 | COMP_Denormal)) {
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if (c & COMP_NaN) {
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EXCEPTION(EX_Invalid);
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f = SW_C3 | SW_C2 | SW_C0;
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} else {
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/* One of the operands is a de-normal */
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return 0;
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}
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} else
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switch (c) {
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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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return 1;
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}
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static int
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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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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 | COMP_Denormal)) {
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if (c & COMP_NaN) {
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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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} else {
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/* One of the operands is a de-normal */
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return control_word & CW_Denormal;
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}
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} else
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switch (c) {
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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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return 1;
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}
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static int
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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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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 | COMP_Denormal)) {
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if (c & COMP_NaN) {
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setcc(SW_C3 | SW_C2 | SW_C0);
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if (c & COMP_SNaN) { /* This is the only difference
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* between un-ordered and
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* ordinary comparisons */
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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 1;
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} else {
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/* One of the operands is a de-normal */
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return control_word & CW_Denormal;
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}
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} else
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switch (c) {
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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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return 1;
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}
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/*---------------------------------------------------------------------------*/
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void
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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
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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
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fcompp()
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{
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/* fcompp */
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if (FPU_rm != 1)
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return Un_impl();
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if (compare_st_st(1)) {
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pop();
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FPU_st0_ptr = &st(0);
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pop();
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}
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}
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void
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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
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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
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fucompp()
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{
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/* fucompp */
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if (FPU_rm == 1) {
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if (compare_u_st_st(1)) {
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pop();
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FPU_st0_ptr = &st(0);
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pop();
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}
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} else
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Un_impl();
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}
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