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/* -*- Mode: Asm -*- */
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/* Copyright (c) 2002 Michael Stumpf <mistumpf@de.pepperl-fuchs.com>
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Copyright (c) 2006,2008 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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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: fp_cmp.S,v 1.4.2.1 2005/12/22 23:16:31 aesok Exp $ */
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fp_cmp.S is part of FPlib V 0.3.0 ported to avr-as
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for details see readme.fplib
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*----------------------------------------------------------------------------------------
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POSSIBILITY OF SUCH DAMAGE. */
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/* $Id: fp_cmp.S,v 1.6.2.1 2008/03/22 04:13:12 dmix Exp $ */
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/* GCC expects all these functions to return -1/0/1 as for __cmpsf2 -
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compare with gcc/config/fp-bit.c (the only difference is with NaNs
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where we should always return nonzero for EQ/NE, -1 for GT/GE,
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1 for LT/LE). -MM 2000-11-18 */
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TEXT_SEG(fplib, __fp_cmp)
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GLOBAL(__eqsf2) ; equal : true, if Z set (and T clear)
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brts .Lfp_cmp_gt ; return 1 (not equal / false) if we got a NaN
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GLOBAL(__gtsf2) ; greater than : true, if Z clear and C clear
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GLOBAL(__cmpsf2) ; returns 1 for A > B ; 0 for A == B ; -1 for A < B ; NaN ?
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/*------------------------------------------------------------------------
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* { C = 1 Z = 0 T = 0 A < B
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* compares x to y and sets flags : { C = 0 Z = 1 T = 0 A == B
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* { C = 0 Z = 0 T = 0 A > B,
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#define ret_lo r24 /* return value (signed byte) */
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.ifnc ret_lo, rA2 ; This is used in __fp_cmp() function.
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/* The base compare function.
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else // isnan(A) || isnan(B)
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BLD rT0,0 ; rT0.7 = sign(A) EOR sign(B), rT0.0 = sign(A)
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RCALL _U(__fp_split2) ; does not return on NaN (T set then)
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RJMP 1f ; different signs
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; same signs : compare
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CPC rA3,rB3 ; A - B ; set Z if equal, sets C if A < B (unsigned)
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BRCC 1f ; A > B (unsigned)
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COM rT0 ; A < B (unsigned)
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1: ; different signs (-0 < +0!)
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; sign(A) == 0 (positive) -> A > B, C = 0 , Z = 0
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; sign(A) == 1 (negative) -> A < B, C = 1 , Z = 0
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ROR rT0 ; C = sign(A)
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sbc r0, r0 ; r0 = (A < 0) ? -1 : 0
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sbc rBE, rBE ; rBE = (B < 0) ? -1 : 0
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ldi ZL, 0x80 ; NaN: 0x{f/7}f800001..0x{f/7}fffffff
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brlo 9f ; branch, if C == 1
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brlo 9f ; branch, if C == 1
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sbc rA3, rB3 ; C is set, if A < B
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; absolute values are equal, check signs
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breq 9f ; if branch, rA2 = 0, C = 0
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brne 2f ; evaluate sign(B)
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; view argument signes
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1: eor r0, rBE ; C is not changed
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brne 2f ; signs are different
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sbci rBE, 1 ; rBE[0] = (A < B && A > 0) ? 0 : 1
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2: lsr rBE ; C = above result OR sign(B)
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; build return value, C is set, if A > B
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adc rA2, r1 ; C = 0 at any case
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removed
libm/fplib/fp_cmp.S
