1/* 2 * Copyright (c) 1983 Regents of the University of California. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms are permitted 6 * provided that the above copyright notice and this paragraph are 7 * duplicated in all such forms and that any documentation, 8 * advertising materials, and other materials related to such 9 * distribution and use acknowledge that the software was developed 10 * by the University of California, Berkeley. The name of the 11 * University may not be used to endorse or promote products derived 12 * from this software without specific prior written permission. 13 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR 14 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED 15 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. 16 */ 17 18#if defined(LIBC_SCCS) && !defined(lint) 19 .asciz "@(#)ldexp.s 5.5 (Berkeley) 05/17/90" 20#endif /* LIBC_SCCS and not lint */ 21 22/* 23 * double ldexp (value, exp) 24 * double value; 25 * int exp; 26 * 27 * Ldexp returns value*2**exp, if that result is in range. 28 * If underflow occurs, it returns zero. If overflow occurs, 29 * it returns a value of appropriate sign and largest 30 * possible magnitude. In case of either overflow or underflow, 31 * errno is set to ERANGE. Note that errno is not modified if 32 * no error occurs. 33 */ 34 35#include "DEFS.h" 36 37/* 38 * don't include errno.h, ANSI C says it defines errno. 39 * 40 * #include <errno.h> 41 */ 42#define ERANGE 34 43 44 .globl _errno 45 46ENTRY(ldexp, 0) 47 movd 4(ap),r0 /* fetch "value" */ 48 extzv $7,$8,r0,r2 /* r2 := biased exponent */ 49 jeql 1f /* if zero, done */ 50 51 addl2 12(ap),r2 /* r2 := new biased exponent */ 52 jleq 2f /* if <= 0, underflow */ 53 cmpl r2,$256 /* otherwise check if too big */ 54 jgeq 3f /* jump if overflow */ 55 insv r2,$7,$8,r0 /* put exponent back in result */ 561: 57 ret 582: 59 clrd r0 60 jbr 1f 613: 62 movd huge,r0 /* largest possible floating magnitude */ 63 jbc $15,4(ap),1f /* jump if argument was positive */ 64 mnegd r0,r0 /* if arg < 0, make result negative */ 651: 66 movl $ERANGE,_errno 67 ret 68 69 .data 70huge: .word 0x7fff /* the largest number that can */ 71 .word 0xffff /* be represented in a long floating */ 72 .word 0xffff /* number. This is given in hex in order */ 73 .word 0xffff /* to avoid floating conversions */ 74