354 lines
		
	
	
		
			9.3 KiB
		
	
	
	
		
			C
		
	
	
	
			
		
		
	
	
			354 lines
		
	
	
		
			9.3 KiB
		
	
	
	
		
			C
		
	
	
	
/*
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 *  x86 FPREM test - executes the FPREM and FPREM1 instructions with corner case
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 *  operands and prints the operands, result and FPU status word.
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 *
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 *  Run this on real hardware, then under QEMU, and diff the outputs, to compare
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 *  QEMU's implementation to your hardware. The 'run-test-i386-fprem' make
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 *  target does this.
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 *
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 *  Copyright (c) 2003 Fabrice Bellard
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 *  Copyright (c) 2012 Catalin Patulea
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 *
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 *  This program is free software; you can redistribute it and/or modify
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 *  it under the terms of the GNU General Public License as published by
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 *  the Free Software Foundation; either version 2 of the License, or
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 *  (at your option) any later version.
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 *
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 *  This program is distributed in the hope that it will be useful,
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 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
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 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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 *  GNU General Public License for more details.
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 *
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 *  You should have received a copy of the GNU General Public License
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 *  along with this program; if not, see <http://www.gnu.org/licenses/>.
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 */
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#include "qemu/compiler.h"
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#include "qemu/osdep.h"
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#include <stdio.h>
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#include <inttypes.h>
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/*
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 * Inspired by <ieee754.h>'s union ieee854_long_double, but with single
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 * long long mantissa fields and assuming little-endianness for simplicity.
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 */
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union float80u {
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    long double d;
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    /* This is the IEEE 854 double-extended-precision format.  */
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    struct {
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        unsigned long long mantissa:63;
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        unsigned int one:1;
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        unsigned int exponent:15;
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        unsigned int negative:1;
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        unsigned int empty:16;
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    } QEMU_PACKED ieee;
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    /* This is for NaNs in the IEEE 854 double-extended-precision format.  */
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    struct {
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        unsigned long long mantissa:62;
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        unsigned int quiet_nan:1;
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        unsigned int one:1;
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        unsigned int exponent:15;
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        unsigned int negative:1;
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        unsigned int empty:16;
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    } QEMU_PACKED ieee_nan;
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};
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#define IEEE854_LONG_DOUBLE_BIAS 0x3fff
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static const union float80u q_nan = {
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    .ieee_nan.negative = 0,  /* X */
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    .ieee_nan.exponent = 0x7fff,
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    .ieee_nan.one = 1,
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    .ieee_nan.quiet_nan = 1,
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    .ieee_nan.mantissa = 0,
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};
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static const union float80u s_nan = {
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    .ieee_nan.negative = 0,  /* X */
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    .ieee_nan.exponent = 0x7fff,
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    .ieee_nan.one = 1,
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    .ieee_nan.quiet_nan = 0,
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    .ieee_nan.mantissa = 1,  /* nonzero */
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};
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static const union float80u pos_inf = {
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    .ieee.negative = 0,
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    .ieee.exponent = 0x7fff,
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    .ieee.one = 1,
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    .ieee.mantissa = 0,
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};
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static const union float80u pseudo_pos_inf = {  /* "unsupported" */
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    .ieee.negative = 0,
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    .ieee.exponent = 0x7fff,
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    .ieee.one = 0,
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    .ieee.mantissa = 0,
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};
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static const union float80u pos_denorm = {
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    .ieee.negative = 0,
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    .ieee.exponent = 0,
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    .ieee.one = 0,
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    .ieee.mantissa = 1,
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};
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static const union float80u smallest_positive_norm = {
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    .ieee.negative = 0,
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    .ieee.exponent = 1,
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    .ieee.one = 1,
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    .ieee.mantissa = 0,
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};
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static void fninit()
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{
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    asm volatile ("fninit\n");
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}
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static long double fprem(long double a, long double b, uint16_t *sw)
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{
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    long double result;
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    asm volatile ("fprem\n"
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                  "fnstsw %1\n"
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                  : "=t" (result), "=m" (*sw)
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                  : "0" (a), "u" (b)
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                  : "st(1)");
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    return result;
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}
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static long double fprem1(long double a, long double b, uint16_t *sw)
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{
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    long double result;
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    asm volatile ("fprem1\n"
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                  "fnstsw %1\n"
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                  : "=t" (result), "=m" (*sw)
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                  : "0" (a), "u" (b)
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                  : "st(1)");
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    return result;
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}
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#define FPUS_IE (1 << 0)
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#define FPUS_DE (1 << 1)
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#define FPUS_ZE (1 << 2)
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#define FPUS_OE (1 << 3)
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#define FPUS_UE (1 << 4)
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#define FPUS_PE (1 << 5)
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#define FPUS_SF (1 << 6)
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#define FPUS_SE (1 << 7)
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#define FPUS_C0 (1 << 8)
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#define FPUS_C1 (1 << 9)
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#define FPUS_C2 (1 << 10)
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#define FPUS_TOP 0x3800
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#define FPUS_C3 (1 << 14)
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#define FPUS_B  (1 << 15)
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#define FPUS_EMASK 0x007f
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#define FPUC_EM 0x3f
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static void psw(uint16_t sw)
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{
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    printf("SW:  C3 TopC2C1C0\n");
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    printf("SW: %c %d %3d %d %d %d %c %c %c %c %c %c %c %c\n",
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           sw & FPUS_B ? 'B' : 'b',
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           !!(sw & FPUS_C3),
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           (sw & FPUS_TOP) >> 11,
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           !!(sw & FPUS_C2),
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           !!(sw & FPUS_C1),
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           !!(sw & FPUS_C0),
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           (sw & FPUS_SE) ? 'S' : 's',
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           (sw & FPUS_SF) ? 'F' : 'f',
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           (sw & FPUS_PE) ? 'P' : 'p',
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           (sw & FPUS_UE) ? 'U' : 'u',
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           (sw & FPUS_OE) ? 'O' : 'o',
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           (sw & FPUS_ZE) ? 'Z' : 'z',
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           (sw & FPUS_DE) ? 'D' : 'd',
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           (sw & FPUS_IE) ? 'I' : 'i');
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}
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static void do_fprem(long double a, long double b)
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{
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    const union float80u au = {.d = a};
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    const union float80u bu = {.d = b};
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    union float80u ru;
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    uint16_t sw;
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    printf("A: S=%d Exp=%04x Int=%d (QNaN=%d) Sig=%016llx (%.06Le)\n",
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           au.ieee.negative, au.ieee.exponent, au.ieee.one,
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           au.ieee_nan.quiet_nan, (unsigned long long)au.ieee.mantissa,
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           a);
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    printf("B: S=%d Exp=%04x Int=%d (QNaN=%d) Sig=%016llx (%.06Le)\n",
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           bu.ieee.negative, bu.ieee.exponent, bu.ieee.one,
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           bu.ieee_nan.quiet_nan, (unsigned long long)bu.ieee.mantissa,
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           b);
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    fflush(stdout);
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    fninit();
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    ru.d = fprem(a, b, &sw);
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    psw(sw);
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    printf("R : S=%d Exp=%04x Int=%d (QNaN=%d) Sig=%016llx (%.06Le)\n",
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           ru.ieee.negative, ru.ieee.exponent, ru.ieee.one,
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           ru.ieee_nan.quiet_nan, (unsigned long long)ru.ieee.mantissa,
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           ru.d);
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    fninit();
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    ru.d = fprem1(a, b, &sw);
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    psw(sw);
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    printf("R1: S=%d Exp=%04x Int=%d (QNaN=%d) Sig=%016llx (%.06Le)\n",
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           ru.ieee.negative, ru.ieee.exponent, ru.ieee.one,
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           ru.ieee_nan.quiet_nan, (unsigned long long)ru.ieee.mantissa,
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           ru.d);
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    printf("\n");
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}
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static void do_fprem_stack_underflow(void)
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{
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    const long double a = 1.0;
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    union float80u ru;
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    uint16_t sw;
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    fninit();
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    asm volatile ("fprem\n"
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                  "fnstsw %1\n"
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                  : "=t" (ru.d), "=m" (sw)
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                  : "0" (a)
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                  : "st(1)");
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    psw(sw);
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    printf("R: S=%d Exp=%04x Int=%d (QNaN=%d) Sig=%016llx (%.06Le)\n",
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           ru.ieee.negative, ru.ieee.exponent, ru.ieee.one,
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           ru.ieee_nan.quiet_nan, (unsigned long long)ru.ieee.mantissa,
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           ru.d);
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    printf("\n");
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}
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static void test_fprem_cases(void)
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{
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    printf("= stack underflow =\n");
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    do_fprem_stack_underflow();
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    printf("= invalid operation =\n");
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    do_fprem(s_nan.d, 1.0);
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    do_fprem(1.0, 0.0);
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    do_fprem(pos_inf.d, 1.0);
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    do_fprem(pseudo_pos_inf.d, 1.0);
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    printf("= denormal =\n");
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    do_fprem(pos_denorm.d, 1.0);
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    do_fprem(1.0, pos_denorm.d);
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    /* printf("= underflow =\n"); */
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    /* TODO: Is there a case where FPREM raises underflow? */
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}
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static void test_fprem_pairs(void)
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{
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    unsigned long long count;
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    unsigned int negative_index_a = 0;
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    unsigned int negative_index_b = 0;
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    static const unsigned int negative_values[] = {
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        0,
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        1,
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    };
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    unsigned int exponent_index_a = 0;
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    unsigned int exponent_index_b = 0;
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    static const unsigned int exponent_values[] = {
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        0,
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        1,
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        2,
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        IEEE854_LONG_DOUBLE_BIAS - 1,
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        IEEE854_LONG_DOUBLE_BIAS,
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        IEEE854_LONG_DOUBLE_BIAS + 1,
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        0x7ffd,
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        0x7ffe,
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        0x7fff,
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    };
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    unsigned int one_index_a = 0;
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    unsigned int one_index_b = 0;
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    static const unsigned int one_values[] = {
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        0,
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        1,
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    };
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    unsigned int quiet_nan_index_a = 0;
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    unsigned int quiet_nan_index_b = 0;
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    static const unsigned int quiet_nan_values[] = {
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        0,
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        1,
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    };
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    unsigned int mantissa_index_a = 0;
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    unsigned int mantissa_index_b = 0;
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    static const unsigned long long mantissa_values[] = {
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        0,
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        1,
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        2,
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        0x3ffffffffffffffdULL,
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        0x3ffffffffffffffeULL,
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        0x3fffffffffffffffULL,
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    };
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    for (count = 0; ; ++count) {
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#define INIT_FIELD(var, field) \
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            .ieee_nan.field = field##_values[field##_index_##var]
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        const union float80u a = {
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            INIT_FIELD(a, negative),
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            INIT_FIELD(a, exponent),
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            INIT_FIELD(a, one),
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            INIT_FIELD(a, quiet_nan),
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            INIT_FIELD(a, mantissa),
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        };
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        const union float80u b = {
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            INIT_FIELD(b, negative),
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            INIT_FIELD(b, exponent),
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            INIT_FIELD(b, one),
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            INIT_FIELD(b, quiet_nan),
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            INIT_FIELD(b, mantissa),
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        };
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#undef INIT_FIELD
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        do_fprem(a.d, b.d);
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        int carry = 1;
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#define CARRY_INTO(var, field) do { \
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            if (carry) { \
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                if (++field##_index_##var == ARRAY_SIZE(field##_values)) { \
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                    field##_index_##var = 0; \
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                } else { \
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                    carry = 0; \
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                } \
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            } \
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        } while (0)
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        CARRY_INTO(b, mantissa);
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        CARRY_INTO(b, quiet_nan);
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        CARRY_INTO(b, one);
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        CARRY_INTO(b, exponent);
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        CARRY_INTO(b, negative);
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        CARRY_INTO(a, mantissa);
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        CARRY_INTO(a, quiet_nan);
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        CARRY_INTO(a, one);
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        CARRY_INTO(a, exponent);
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        CARRY_INTO(a, negative);
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#undef CARRY_INTO
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        if (carry) {
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            break;
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        }
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    }
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    fprintf(stderr, "test-i386-fprem: tested %llu cases\n", count);
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}
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int main(int argc, char **argv)
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{
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    test_fprem_cases();
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    test_fprem_pairs();
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    return 0;
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}
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