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+/*
+ * reg_compare.c
+ *
+ * Compare two floating point registers
+ *
+ *
+ * Copyright (C) 1992,1993,1994
+ * W. Metzenthen, 22 Parker St, Ormond, Vic 3163,
+ * Australia. E-mail billm@vaxc.cc.monash.edu.au
+ * All rights reserved.
+ *
+ * This copyright notice covers the redistribution and use of the
+ * FPU emulator developed by W. Metzenthen. It covers only its use
+ * in the 386BSD, FreeBSD and NetBSD operating systems. Any other
+ * use is not permitted under this copyright.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must include information specifying
+ * that source code for the emulator is freely available and include
+ * either:
+ * a) an offer to provide the source code for a nominal distribution
+ * fee, or
+ * b) list at least two alternative methods whereby the source
+ * can be obtained, e.g. a publically accessible bulletin board
+ * and an anonymous ftp site from which the software can be
+ * downloaded.
+ * 3. All advertising materials specifically mentioning features or use of
+ * this emulator must acknowledge that it was developed by W. Metzenthen.
+ * 4. The name of W. Metzenthen may not be used to endorse or promote
+ * products derived from this software without specific prior written
+ * permission.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+ * W. METZENTHEN BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ *
+ * The purpose of this copyright, based upon the Berkeley copyright, is to
+ * ensure that the covered software remains freely available to everyone.
+ *
+ * The software (with necessary differences) is also available, but under
+ * the terms of the GNU copyleft, for the Linux operating system and for
+ * the djgpp ms-dos extender.
+ *
+ * W. Metzenthen June 1994.
+ *
+ *
+ * $Id: reg_compare.c,v 1.3 1994/06/10 07:44:47 rich Exp $
+ *
+ */
+
+/*---------------------------------------------------------------------------+
+ | compare() is the core FPU_REG comparison function |
+ +---------------------------------------------------------------------------*/
+#include "param.h"
+#include "proc.h"
+#include "systm.h"
+#include "machine/cpu.h"
+#include "machine/pcb.h"
+
+#include "fpu_emu.h"
+#include "fpu_system.h"
+#include "exception.h"
+#include "control_w.h"
+#include "status_w.h"
+
+
+int
+compare(FPU_REG * b)
+{
+ int diff;
+
+ if (FPU_st0_ptr->tag | b->tag) {
+ if (FPU_st0_ptr->tag == TW_Zero) {
+ if (b->tag == TW_Zero)
+ return COMP_A_eq_B;
+ if (b->tag == TW_Valid) {
+#ifdef DENORM_OPERAND
+ if ((b->exp <= EXP_UNDER) && (denormal_operand()))
+ return COMP_Denormal;
+#endif /* DENORM_OPERAND */
+ return (b->sign == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B;
+ }
+ } else
+ if (b->tag == TW_Zero) {
+ if (FPU_st0_ptr->tag == TW_Valid) {
+#ifdef DENORM_OPERAND
+ if ((FPU_st0_ptr->exp <= EXP_UNDER) && (denormal_operand()))
+ return COMP_Denormal;
+#endif /* DENORM_OPERAND */
+ return (FPU_st0_ptr->sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B;
+ }
+ }
+ if (FPU_st0_ptr->tag == TW_Infinity) {
+ if ((b->tag == TW_Valid) || (b->tag == TW_Zero)) {
+#ifdef DENORM_OPERAND
+ if ((b->tag == TW_Valid) && (b->exp <= EXP_UNDER)
+ && (denormal_operand()))
+ return COMP_Denormal;
+#endif /* DENORM_OPERAND */
+ return (FPU_st0_ptr->sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B;
+ } else
+ if (b->tag == TW_Infinity) {
+ /* The 80486 book says that infinities
+ * can be equal! */
+ return (FPU_st0_ptr->sign == b->sign) ? COMP_A_eq_B :
+ ((FPU_st0_ptr->sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B);
+ }
+ /* Fall through to the NaN code */
+ } else
+ if (b->tag == TW_Infinity) {
+ if ((FPU_st0_ptr->tag == TW_Valid) || (FPU_st0_ptr->tag == TW_Zero)) {
+#ifdef DENORM_OPERAND
+ if ((FPU_st0_ptr->tag == TW_Valid)
+ && (FPU_st0_ptr->exp <= EXP_UNDER)
+ && (denormal_operand()))
+ return COMP_Denormal;
+#endif /* DENORM_OPERAND */
+ return (b->sign == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B;
+ }
+ /* Fall through to the NaN code */
+ }
+ /* The only possibility now should be that one of the
+ * arguments is a NaN */
+ if ((FPU_st0_ptr->tag == TW_NaN) || (b->tag == TW_NaN)) {
+ if (((FPU_st0_ptr->tag == TW_NaN) && !(FPU_st0_ptr->sigh & 0x40000000))
+ || ((b->tag == TW_NaN) && !(b->sigh & 0x40000000)))
+ /* At least one arg is a signaling NaN */
+ return COMP_No_Comp | COMP_SNaN | COMP_NaN;
+ else
+ /* Neither is a signaling NaN */
+ return COMP_No_Comp | COMP_NaN;
+ }
+ EXCEPTION(EX_Invalid);
+ }
+#ifdef PARANOID
+ if (!(FPU_st0_ptr->sigh & 0x80000000))
+ EXCEPTION(EX_Invalid);
+ if (!(b->sigh & 0x80000000))
+ EXCEPTION(EX_Invalid);
+#endif /* PARANOID */
+
+#ifdef DENORM_OPERAND
+ if (((FPU_st0_ptr->exp <= EXP_UNDER) ||
+ (b->exp <= EXP_UNDER)) && (denormal_operand()))
+ return COMP_Denormal;
+#endif /* DENORM_OPERAND */
+
+ if (FPU_st0_ptr->sign != b->sign)
+ return (FPU_st0_ptr->sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B;
+
+ diff = FPU_st0_ptr->exp - b->exp;
+ if (diff == 0) {
+ diff = FPU_st0_ptr->sigh - b->sigh; /* Works only if ms bits
+ * are identical */
+ if (diff == 0) {
+ diff = FPU_st0_ptr->sigl > b->sigl;
+ if (diff == 0)
+ diff = -(FPU_st0_ptr->sigl < b->sigl);
+ }
+ }
+ if (diff > 0)
+ return (FPU_st0_ptr->sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B;
+ if (diff < 0)
+ return (FPU_st0_ptr->sign == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B;
+ return COMP_A_eq_B;
+
+}
+
+
+/* This function requires that st(0) is not empty */
+int
+compare_st_data(void)
+{
+ int f, c;
+
+ c = compare(&FPU_loaded_data);
+
+ if (c & (COMP_NaN | COMP_Denormal)) {
+ if (c & COMP_NaN) {
+ EXCEPTION(EX_Invalid);
+ f = SW_C3 | SW_C2 | SW_C0;
+ } else {
+ /* One of the operands is a de-normal */
+ return 0;
+ }
+ } else
+ switch (c) {
+ 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);
+ return 1;
+}
+
+
+static int
+compare_st_st(int nr)
+{
+ int f, c;
+
+ if (!NOT_EMPTY_0 || !NOT_EMPTY(nr)) {
+ setcc(SW_C3 | SW_C2 | SW_C0);
+ /* Stack fault */
+ EXCEPTION(EX_StackUnder);
+ return control_word & CW_Invalid;
+ }
+ c = compare(&st(nr));
+ if (c & (COMP_NaN | COMP_Denormal)) {
+ if (c & COMP_NaN) {
+ setcc(SW_C3 | SW_C2 | SW_C0);
+ EXCEPTION(EX_Invalid);
+ return control_word & CW_Invalid;
+ } else {
+ /* One of the operands is a de-normal */
+ return control_word & CW_Denormal;
+ }
+ } else
+ switch (c) {
+ 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);
+ return 1;
+}
+
+
+static int
+compare_u_st_st(int nr)
+{
+ int f, c;
+
+ if (!NOT_EMPTY_0 || !NOT_EMPTY(nr)) {
+ setcc(SW_C3 | SW_C2 | SW_C0);
+ /* Stack fault */
+ EXCEPTION(EX_StackUnder);
+ return control_word & CW_Invalid;
+ }
+ c = compare(&st(nr));
+ if (c & (COMP_NaN | COMP_Denormal)) {
+ 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 1;
+ } else {
+ /* One of the operands is a de-normal */
+ return control_word & CW_Denormal;
+ }
+ } else
+ switch (c) {
+ 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);
+ return 1;
+}
+/*---------------------------------------------------------------------------*/
+
+void
+fcom_st()
+{
+ /* fcom st(i) */
+ compare_st_st(FPU_rm);
+}
+
+
+void
+fcompst()
+{
+ /* fcomp st(i) */
+ if (compare_st_st(FPU_rm))
+ pop();
+}
+
+
+void
+fcompp()
+{
+ /* fcompp */
+ if (FPU_rm != 1)
+ return Un_impl();
+ if (compare_st_st(1)) {
+ pop();
+ FPU_st0_ptr = &st(0);
+ pop();
+ }
+}
+
+
+void
+fucom_()
+{
+ /* fucom st(i) */
+ compare_u_st_st(FPU_rm);
+
+}
+
+
+void
+fucomp()
+{
+ /* fucomp st(i) */
+ if (compare_u_st_st(FPU_rm))
+ pop();
+}
+
+
+void
+fucompp()
+{
+ /* fucompp */
+ if (FPU_rm == 1) {
+ if (compare_u_st_st(1)) {
+ pop();
+ FPU_st0_ptr = &st(0);
+ pop();
+ }
+ } else
+ Un_impl();
+}
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