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1.1 root 1: /*-
2: * Copyright (c) 1985 The Regents of the University of California.
3: * All rights reserved.
4: *
5: * This code is derived from software contributed to Berkeley by
6: * Computer Consoles Inc.
7: *
8: * Redistribution and use in source and binary forms, with or without
9: * modification, are permitted provided that the following conditions
10: * are met:
11: * 1. Redistributions of source code must retain the above copyright
12: * notice, this list of conditions and the following disclaimer.
13: * 2. Redistributions in binary form must reproduce the above copyright
14: * notice, this list of conditions and the following disclaimer in the
15: * documentation and/or other materials provided with the distribution.
16: * 3. All advertising materials mentioning features or use of this software
17: * must display the following acknowledgement:
18: * This product includes software developed by the University of
19: * California, Berkeley and its contributors.
20: * 4. Neither the name of the University nor the names of its contributors
21: * may be used to endorse or promote products derived from this software
22: * without specific prior written permission.
23: *
24: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34: * SUCH DAMAGE.
35: *
36: * @(#)Kcvtlf.s 7.1 (Berkeley) 12/6/90
37: */
38:
39: #include "../math/fp.h"
40: #include "../math/Kfp.h"
41: #include "../tahoe/SYS.h"
42:
43: .text
44: ENTRY(Kcvtlf, R5|R4|R3|R2)
45: clrl r1
46: clrl r4 # r4 - negative flag.
47: clrl r2 # r2 - exponent.
48: movl 12(fp),r0 # fetch operand.
49: movl r0,r5 # need another copy.
50: jeql retzero # return zero.
51: jgtr positive
52: mnegl r0,r0
53: jvs retmin # return minimum integer.
54: incl r4 # remember it was negative.
55: movl r0,r5 # remember the negated value.
56: #
57: #Compute exponent:
58: #
59: positive:
60: ffs r0,r1
61: incl r1
62: addl2 r1,r2
63: shrl r1,r0,r0
64: jneq positive # look for more set bits.
65: #
66: #we have the exponent in r2.
67: #
68: movl r5,r0 # r0 will hold the resulting f.p. number.
69: #
70: #Shift the fraction part to its proper place:
71: #
72: subl3 r2,$HID_POS,r3
73: jlss shiftr # if less then zero we have to shift right.
74: shll r3,r0,r0 # else we shift left.
75: jmp shifted
76: shiftr:
77: mnegl r3,r3
78: shrl r3,r0,r0
79: shifted:
80: andl2 $CLEARHID,r0 # clear the hidden bit.
81: shal $EXPSHIFT,r2,r2 # shift the exponent to its proper place.
82: orl2 $EXPSIGN,r2 # set the exponent sign bit(to bias it).
83: orl2 r2,r0 # combine exponent & fraction.
84: bbc $0,r4,sign_ok # do we have to set the sign bit?
85: orl2 $SIGNBIT,r0 # yes...
86: sign_ok:
87: ret
88:
89: retzero:
90: clrl r0
91: ret
92:
93: retmin:
94: movl $0xd0000000,r0
95: ret
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