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| Commit | Line | Data |
|---|---|---|
| 9d1834ba | 1 | /* Kcvtfl.s 1.3 86/01/05 */ |
| 77c2882f | 2 | |
| 9d1834ba SL |
3 | #include "../tahoemath/fp.h" |
| 4 | #include "../tahoe/SYS.h" | |
| 77c2882f | 5 | |
| 2b252132 SL |
6 | .text |
| 7 | ENTRY(Kcvtfl, R5|R4|R3|R2) | |
| 77c2882f SL |
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 | # | |
| 22 | positive: | |
| 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 | |
| 39 | shiftr: | |
| 40 | mnegl r3,r3 | |
| 41 | shrl r3,r0,r0 | |
| 42 | shifted: | |
| 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... | |
| 49 | sign_ok: | |
| 50 | ret | |
| 51 | ||
| 52 | retzero: | |
| 53 | clrl r0 | |
| 54 | ret | |
| 55 | ||
| 56 | retmin: | |
| 57 | movl $0xd0000000,r0 | |
| 58 | ret |