1 /*- 2 * Copyright (c) 1992 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * This software was developed by the Computer Systems Engineering group 6 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and 7 * contributed to Berkeley. 8 * 9 * %sccs.include.redist.c% 10 */ 11 12 #if defined(LIBC_SCCS) && !defined(lint) 13 static char sccsid[] = "@(#)ashrdi3.c 5.5 (Berkeley) 06/02/92"; 14 #endif /* LIBC_SCCS and not lint */ 15 16 #include "quad.h" 17 18 /* 19 * Shift a (signed) quad value right (arithmetic shift right). 20 */ 21 quad 22 __ashrdi3(quad a, u_quad shift) 23 { 24 union uu aa; 25 26 aa.q = a; 27 if (shift >= LONG_BITS) { 28 long s; 29 30 /* 31 * Smear bits rightward using the machine's right-shift 32 * method, whether that is sign extension or zero fill, 33 * to get the `sign word' s. Note that shifting by 34 * LONG_BITS is undefined, so we shift (LONG_BITS-1), 35 * then 1 more, to get our answer. 36 */ 37 s = (aa.sl[H] >> (LONG_BITS - 1)) >> 1; 38 aa.ul[L] = shift >= QUAD_BITS ? s : 39 aa.sl[H] >> (shift - LONG_BITS); 40 aa.ul[H] = s; 41 } else if (shift > 0) { 42 aa.ul[L] = (aa.ul[L] >> shift) | 43 (aa.ul[H] << (LONG_BITS - shift)); 44 aa.sl[H] >>= shift; 45 } 46 return (aa.q); 47 } 48