arch/m68k-all/libgcc1/_fixsfsi.s

   1 | single float to long conversion routine
   2 |
   3
   4 BIAS4   =       0x7F-1
   5
   6         .text
   7         .even
   8         .globl  __fixsfsi
   9
  10 __fixsfsi:
  11         lea     %sp@(4),%a0     | pointer to parameters
  12         moveml  %d2/%d4/%d5,%sp@-       | save registers
  13         movel   %a0@,%d4                | get the number
  14         movew   %a0@,%d0                | extract exp
  15         movew   %d0,%d2         | extract sign
  16         lsrw    #7,%d0
  17         andw    #0xff,%d0       | kill sign bit
  18
  19         andl    #0x7fffff,%d4   | remove exponent from mantissa
  20         orl     #0x800000,%d4   | restore implied leading "1"
  21
  22         cmpw    #BIAS4,%d0      | check exponent
  23         blt     zero            | strictly factional, no integer part ?
  24         cmpw    #BIAS4+32,%d0   | is it too big to fit in a 32-bit integer ?
  25         bgt     toobig
  26
  27         subw    #BIAS4+24,%d0   | adjust exponent
  28         bgt     L_2             | shift up
  29         beq     L_3             | no shift
  30
  31         cmpw    #-8,%d0         | replace far shifts by swap
  32         bgt     L_1
  33         movew   %d4,%d5         | shift fast, 16 bits
  34         swap    %d5
  35         clrw    %d4
  36         swap    %d4
  37         addw    #16,%d0         | account for swap
  38         bgt     L_2
  39         beq     L_3
  40
  41 L_1:    lsrl    #1,%d4          | shift down to align radix point;
  42         addw    #1,%d0          | extra bits fall off the end (no rounding)
  43         blt     L_1             | shifted all the way down yet ?
  44         bra     L_3
  45
  46 L_2:    addl    %d5,%d5         | shift up to align radix point
  47         addxl   %d4,%d4
  48         subw    #1,%d0
  49         bgt     L_2
  50
  51 L_3:    movel   %d4,%d0         | put integer into result register
  52         cmpl    #0x80000000,%d0 | -2147483648 is a nasty evil special case
  53         bne     L_6
  54         tstw    %d2             | this had better be -2^31 and not 2^31
  55         bpl     toobig
  56         bra     L_8
  57 L_6:    tstl    %d0             | sign bit set ? (i.e. too big)
  58         bmi     toobig
  59 L_7:
  60         tstw    %d2             | is it negative ?
  61         bpl     L_8
  62         negl    %d0             | negate
  63 L_8:
  64         moveml  %sp@+,%d2/%d4/%d5
  65         rts
  66
  67 zero:
  68         clrl    %d0             | make the whole thing zero
  69         bra     L_7
  70
  71 toobig:
  72         movel   #0x7fffffff,%d0 | ugh. Should cause a trap here.
  73         bra     L_7