1/* Kcvtld.s 1.2 86/01/03 */ 2 3#include "fp.h" 4#include "Kfp.h" 5#include "SYS.h" 6 7 .text 8ENTRY(Kcvtld, R5|R4|R3|R2) 9 clrl r4 # r4 - negative flag. 10 clrl r2 # r2 - exponent. 11 movl 12(fp),r0 # fetch operand. 12 movl r0,r5 # need another copy. 13 jeql retzero # return zero. 14 jgtr positive 15 mnegl r0,r0 16 jvs retmin # return minimum integer. 17 incl r4 # remember it was negative. 18 movl r0,r5 # remember the negated value. 19 # 20 #Compute exponent: 21 # 22positive: 23 ffs r0,r1 24 incl r1 25 addl2 r1,r2 26 shrl r1,r0,r0 27 jneq positive # look for more set bits. 28 # 29 #we have the exponent in r2. 30 # 31 movl r5,r0 # r0,r1 will hold the resulting f.p. number. 32 clrl r1 33 # 34 #Shift the fraction part to its proper place: 35 # 36 subl3 r2,$HID_POS,r3 37 jlss shiftr # if less then zero we have to shift right. 38 shll r3,r0,r0 # else we shift left. 39 jmp shifted 40shiftr: 41 mnegl r3,r3 42 shrq r3,r0,r0 43shifted: 44 andl2 $CLEARHID,r0 # clear the hidden bit. 45 shal $EXPSHIFT,r2,r2 # shift the exponent to its proper place. 46 orl2 $EXPSIGN,r2 # set the exponent sign bit(to bias it). 47 orl2 r2,r0 # combine exponent & fraction. 48 bbc $0,r4,sign_ok # do we have to set the sign bit? 49 orl2 $SIGNBIT,r0 # yes... 50sign_ok: 51 ret 52 53retzero: 54 clrl r0 55 clrl r1 56 ret 57 58retmin: 59 movl $0xd0000000,r0 60 clrl r1 61 ret 62 63 64 65