1/* 2 * Copyright (c) 1986 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 * %sccs.include.redist.c% 9 */ 10 11#if defined(SYSLIBC_SCCS) && !defined(lint) 12 .asciz "@(#)cvtud.s 1.3 (Berkeley) 06/01/90" 13#endif /* SYSLIBC_SCCS and not lint */ 14 15#include <tahoemath/fp.h> 16#include "DEFS.h" 17 18XENTRY(cvtud, R2|R3|R4|R5) 19 # 20 # Some initializations: 21 # 22 clrl r2 # r2 - exponent. 23 movl 4(fp),r0 # fetch operand. 24 jeql retzero # return zero. 25 # 26 # Compute exponent: 27 # 28positive: 29 ffs r0,r1 30 incl r1 31 addl2 r1,r2 32 shrl r1,r0,r0 33 jneq positive # look for more set bits. 34 # 35 # we have the exponent in r2. 36 # 37 movl 4(fp),r0 # r0,r1 will hold the resulting f.p. number. 38 clrl r1 39 # 40 # Shift the fraction part to its proper place: 41 # 42 subl3 r2,$HID_POS,r3 43 jlss shiftr # if less then zero we have to shift right. 44 shll r3,r0,r0 # else we shift left. 45 jmp shifted 46shiftr: 47 mnegl r3,r3 48 shrq r3,r0,r0 49shifted: 50 andl2 $CLEARHID,r0 # clear the hidden bit. 51 shal $EXPSHIFT,r2,r2 # shift the exponent to its proper place. 52 orl2 $EXPSIGN,r2 # set the exponent sign bit(to bias it). 53 orl2 r2,r0 # combine exponent & fraction. 54sign_ok: 55 ret 56 57retzero: 58 clrl r0 59 clrl r1 60 ret 61 62 63