1/* Kcvtfl.s 1.2 86/01/03 */ 2 3#include "fp.h" 4#include "SYS.h" 5 6 .text 7ENTRY(Kcvtfl, R5|R4|R3|R2) 8 clrl r1 9 clrl r4 # r4 - negative flag. 10 clrl r2 # r2 - exponent. 11 movl 4(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 will hold the resulting f.p. number. 32 # 33 #Shift the fraction part to its proper place: 34 # 35 subl3 r2,$HID_POS,r3 36 jlss shiftr # if less then zero we have to shift right. 37 shll r3,r0,r0 # else we shift left. 38 jmp shifted 39shiftr: 40 mnegl r3,r3 41 shrl r3,r0,r0 42shifted: 43 andl2 $CLEARHID,r0 # clear the hidden bit. 44 shal $EXPSHIFT,r2,r2 # shift the exponent to its proper place. 45 orl2 $EXPSIGN,r2 # set the exponent sign bit(to bias it). 46 orl2 r2,r0 # combine exponent & fraction. 47 bbc $0,r4,sign_ok # do we have to set the sign bit? 48 orl2 $SIGNBIT,r0 # yes... 49sign_ok: 50 ret 51 52retzero: 53 clrl r0 54 ret 55 56retmin: 57 movl $0xd0000000,r0 58 ret 59