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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/m68k/fpsp040/sgetem.S
downloadconfigs-2.6.12-rc2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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+|
+| sgetem.sa 3.1 12/10/90
+|
+| The entry point sGETEXP returns the exponent portion
+| of the input argument. The exponent bias is removed
+| and the exponent value is returned as an extended
+| precision number in fp0. sGETEXPD handles denormalized
+| numbers.
+|
+| The entry point sGETMAN extracts the mantissa of the
+| input argument. The mantissa is converted to an
+| extended precision number and returned in fp0. The
+| range of the result is [1.0 - 2.0).
+|
+|
+| Input: Double-extended number X in the ETEMP space in
+| the floating-point save stack.
+|
+| Output: The functions return exp(X) or man(X) in fp0.
+|
+| Modified: fp0.
+|
+|
+| Copyright (C) Motorola, Inc. 1990
+| All Rights Reserved
+|
+| THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA
+| The copyright notice above does not evidence any
+| actual or intended publication of such source code.
+
+|SGETEM idnt 2,1 | Motorola 040 Floating Point Software Package
+
+ |section 8
+
+#include "fpsp.h"
+
+ |xref nrm_set
+
+|
+| This entry point is used by the unimplemented instruction exception
+| handler. It points a0 to the input operand.
+|
+|
+|
+| SGETEXP
+|
+
+ .global sgetexp
+sgetexp:
+ movew LOCAL_EX(%a0),%d0 |get the exponent
+ bclrl #15,%d0 |clear the sign bit
+ subw #0x3fff,%d0 |subtract off the bias
+ fmovew %d0,%fp0 |move the exp to fp0
+ rts
+
+ .global sgetexpd
+sgetexpd:
+ bclrb #sign_bit,LOCAL_EX(%a0)
+ bsr nrm_set |normalize (exp will go negative)
+ movew LOCAL_EX(%a0),%d0 |load resulting exponent into d0
+ subw #0x3fff,%d0 |subtract off the bias
+ fmovew %d0,%fp0 |move the exp to fp0
+ rts
+|
+|
+| This entry point is used by the unimplemented instruction exception
+| handler. It points a0 to the input operand.
+|
+|
+|
+| SGETMAN
+|
+|
+| For normalized numbers, leave the mantissa alone, simply load
+| with an exponent of +/- $3fff.
+|
+ .global sgetman
+sgetman:
+ movel USER_FPCR(%a6),%d0
+ andil #0xffffff00,%d0 |clear rounding precision and mode
+ fmovel %d0,%fpcr |this fpcr setting is used by the 882
+ movew LOCAL_EX(%a0),%d0 |get the exp (really just want sign bit)
+ orw #0x7fff,%d0 |clear old exp
+ bclrl #14,%d0 |make it the new exp +-3fff
+ movew %d0,LOCAL_EX(%a0) |move the sign & exp back to fsave stack
+ fmovex (%a0),%fp0 |put new value back in fp0
+ rts
+
+|
+| For denormalized numbers, shift the mantissa until the j-bit = 1,
+| then load the exponent with +/1 $3fff.
+|
+ .global sgetmand
+sgetmand:
+ movel LOCAL_HI(%a0),%d0 |load ms mant in d0
+ movel LOCAL_LO(%a0),%d1 |load ls mant in d1
+ bsr shft |shift mantissa bits till msbit is set
+ movel %d0,LOCAL_HI(%a0) |put ms mant back on stack
+ movel %d1,LOCAL_LO(%a0) |put ls mant back on stack
+ bras sgetman
+
+|
+| SHFT
+|
+| Shifts the mantissa bits until msbit is set.
+| input:
+| ms mantissa part in d0
+| ls mantissa part in d1
+| output:
+| shifted bits in d0 and d1
+shft:
+ tstl %d0 |if any bits set in ms mant
+ bnes upper |then branch
+| ;else no bits set in ms mant
+ tstl %d1 |test if any bits set in ls mant
+ bnes cont |if set then continue
+ bras shft_end |else return
+cont:
+ movel %d3,-(%a7) |save d3
+ exg %d0,%d1 |shift ls mant to ms mant
+ bfffo %d0{#0:#32},%d3 |find first 1 in ls mant to d0
+ lsll %d3,%d0 |shift first 1 to integer bit in ms mant
+ movel (%a7)+,%d3 |restore d3
+ bras shft_end
+upper:
+
+ moveml %d3/%d5/%d6,-(%a7) |save registers
+ bfffo %d0{#0:#32},%d3 |find first 1 in ls mant to d0
+ lsll %d3,%d0 |shift ms mant until j-bit is set
+ movel %d1,%d6 |save ls mant in d6
+ lsll %d3,%d1 |shift ls mant by count
+ movel #32,%d5
+ subl %d3,%d5 |sub 32 from shift for ls mant
+ lsrl %d5,%d6 |shift off all bits but those that will
+| ;be shifted into ms mant
+ orl %d6,%d0 |shift the ls mant bits into the ms mant
+ moveml (%a7)+,%d3/%d5/%d6 |restore registers
+shft_end:
+ rts
+
+ |end