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134 lines
4.4 KiB
ArmAsm
134 lines
4.4 KiB
ArmAsm
/* long double floor function.
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IBM extended format long double version.
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Copyright (C) 2004, 2006 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library 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 GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <sysdep.h>
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#include <math_ldbl_opt.h>
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.section ".toc","aw"
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.LC0: /* 2**52 */
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.tc FD_43300000_0[TC],0x4330000000000000
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.section ".text"
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/* long double [fp1,fp2] floorl (long double x [fp1,fp2])
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IEEE 1003.1 floor function.
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PowerPC64 long double uses the IBM extended format which is
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represented two 64-floating point double values. The values are
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non-overlapping giving an effective precision of 106 bits. The first
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double contains the high order bits of mantisa and is always rounded
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to represent a normal rounding of long double to double. Since the
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long double value is sum of the high and low values, the low double
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normally has the opposite sign to compensate for the this rounding.
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For long double there are two cases:
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1) |x| < 2**52, all the integer bits are in the high double.
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floor the high double and set the low double to -0.0.
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2) |x| >= 2**52, Rounding involves both doubles.
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See the comment before lable .L2 for details.
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*/
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ENTRY (__floorl)
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mffs fp11 /* Save current FPU rounding mode. */
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lfd fp13,.LC0@toc(2)
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fabs fp0,fp1
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fabs fp9,fp2
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fsub fp12,fp13,fp13 /* generate 0.0 */
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fcmpu cr7,fp0,fp13 /* if (fabs(x) > TWO52) */
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fcmpu cr6,fp1,fp12 /* if (x > 0.0) */
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bnl- cr7,.L2
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mtfsfi 7,3 /* Set rounding mode toward -inf. */
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fneg fp2,fp12 /* set low double to -0.0. */
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ble- cr6,.L0
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fadd fp1,fp1,fp13 /* x+= TWO52; */
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fsub fp1,fp1,fp13 /* x-= TWO52; */
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fcmpu cr5,fp1,fp12 /* if (x > 0.0) */
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mtfsf 0x01,fp11 /* restore previous rounding mode. */
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bnelr+ cr5
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fmr fp1,fp12 /* x must be +0.0 for the 0.0 case. */
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blr
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.L0:
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bge- cr6,.L1 /* if (x < 0.0) */
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fsub fp1,fp1,fp13 /* x-= TWO52; */
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fadd fp1,fp1,fp13 /* x+= TWO52; */
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.L1:
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mtfsf 0x01,fp11 /* restore previous rounding mode. */
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blr
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/* The high double is > TWO52 so we need to round the low double and
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perhaps the high double. In this case we have to round the low
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double and handle any adjustment to the high double that may be
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caused by rounding (up). This is complicated by the fact that the
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high double may already be rounded and the low double may have the
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opposite sign to compensate.This gets a bit tricky so we use the
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following algorithm:
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tau = floor(x_high/TWO52);
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x0 = x_high - tau;
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x1 = x_low + tau;
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r1 = rint(x1);
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y_high = x0 + r1;
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y_low = x0 - y_high + r1;
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return y; */
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.L2:
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fcmpu cr7,fp9,fp13 /* if (|x_low| > TWO52) */
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fcmpu cr0,fp9,fp12 /* || (|x_low| == 0.0) */
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fcmpu cr5,fp2,fp12 /* if (x_low > 0.0) */
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bgelr- cr7 /* return x; */
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beqlr- cr0
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mtfsfi 7,3 /* Set rounding mode toward -inf. */
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fdiv fp8,fp1,fp13 /* x_high/TWO52 */
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bng- cr6,.L6 /* if (x > 0.0) */
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fctidz fp0,fp8
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fcfid fp8,fp0 /* tau = floor(x_high/TWO52); */
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bng cr5,.L4 /* if (x_low > 0.0) */
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fmr fp3,fp1
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fmr fp4,fp2
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b .L5
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.L4: /* if (x_low < 0.0) */
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fsub fp3,fp1,fp8 /* x0 = x_high - tau; */
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fadd fp4,fp2,fp8 /* x1 = x_low + tau; */
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.L5:
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fadd fp5,fp4,fp13 /* r1 = r1 + TWO52; */
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fsub fp5,fp5,fp13 /* r1 = r1 - TWO52; */
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b .L9
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.L6: /* if (x < 0.0) */
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fctidz fp0,fp8
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fcfid fp8,fp0 /* tau = floor(x_high/TWO52); */
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bnl cr5,.L7 /* if (x_low < 0.0) */
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fmr fp3,fp1
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fmr fp4,fp2
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b .L8
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.L7: /* if (x_low > 0.0) */
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fsub fp3,fp1,fp8 /* x0 = x_high - tau; */
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fadd fp4,fp2,fp8 /* x1 = x_low + tau; */
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.L8:
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fsub fp5,fp4,fp13 /* r1-= TWO52; */
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fadd fp5,fp5,fp13 /* r1+= TWO52; */
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.L9:
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mtfsf 0x01,fp11 /* restore previous rounding mode. */
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fadd fp1,fp3,fp5 /* y_high = x0 + r1; */
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fsub fp2,fp3,fp1 /* y_low = x0 - y_high + r1; */
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fadd fp2,fp2,fp5
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blr
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END (__floorl)
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long_double_symbol (libm, __floorl, floorl)
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