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/* Copyright (c) 2007 Dmitry Xmelkov
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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 are met:
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* 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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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in
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the documentation and/or other materials provided with the
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* Neither the name of the copyright holders nor the names of
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contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE. */
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/* $Id: lrint.S,v 1.1 2007/12/01 04:39:05 dmix Exp $ */
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/* long lrint (double A);
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The lrint() function rounds A to the nearest integer, rounding the
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halfway cases to the even integer direction. (That is both 1.5 and
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2.5 values are rounded to 2). This function is similar to rint()
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function, but it differs in type of return value and in that an
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The rounded long integer value. If A is not a finite number or an
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overflow was, this realization returns the LONG_MIN value (0x80000000).
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- shift mantissa according to exponent
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- round (if shift was to right)
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subi rA3, 126 ; exponent field of 0.5
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brlo .L_zr ; A is too small
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; fabs(A) >= 0x0.800000p+00
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brlo .L_right ; shtft to right and round
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breq .L_sign ; no shift
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; fabs(A) >= 0x0.800000p+25
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brsh .L_err ; fabs(A) is too big
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; 0x0.800000p+25 <= fabs(A) <= 0x0.ffffffp+31 --> shift to left by 1..7
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mov r0, rA3 ; shift counter
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; 0x0.800000p+00 <= fabs(A) <= 0x0.ffffffp+23
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; Shift A to right by 1 (rA3 == -1) .. 24 (rA3 == -24) positions and
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clr rAE ; accumulator for lower bits
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; Quick shift to right by 8. The trick with rAE is needed to save info
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; about the lowerest bits. This will be used to compare fraction with
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; shift to right by 1..7 (slow)
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ori rAE, 1 ; save flag that lowerst bits are not all 0
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brcc .L_sign ; fraction < 0.5
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brne 7f ; fraction > 0.5
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rjmp .L_sign ; fraction == 0.5 and value is even
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sbci rA2, -1 ; rA2 was <= 0x7f, so rA3 will not changed
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; restore the sign and return
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.L_err: set ; force return 0x80000000
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.L_zr: rjmp _U(__fp_zero) ; return 0x00000000
added
removed
libm/fplib/lrint.S
