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systmodes.S revision 1.1.1.1 
      1 
      2 /*
      3 ===============================================================================
      4 
      5 This GNU assembler source file is part of TestFloat, Release 2a, a package
      6 of programs for testing the correctness of floating-point arithmetic
      7 complying to the IEC/IEEE Standard for Floating-Point.
      8 
      9 Written by John R. Hauser.  More information is available through the Web
     10 page `http://HTTP.CS.Berkeley.EDU/~jhauser/arithmetic/TestFloat.html'.
     11 
     12 THIS SOFTWARE IS DISTRIBUTED AS IS, FOR FREE.  Although reasonable effort
     13 has been made to avoid it, THIS SOFTWARE MAY CONTAIN FAULTS THAT WILL AT
     14 TIMES RESULT IN INCORRECT BEHAVIOR.  USE OF THIS SOFTWARE IS RESTRICTED TO
     15 PERSONS AND ORGANIZATIONS WHO CAN AND WILL TAKE FULL RESPONSIBILITY FOR ANY
     16 AND ALL LOSSES, COSTS, OR OTHER PROBLEMS ARISING FROM ITS USE.
     17 
     18 Derivative works are acceptable, even for commercial purposes, so long as
     19 (1) they include prominent notice that the work is derivative, and (2) they
     20 include prominent notice akin to these four paragraphs for those parts of
     21 this code that are retained.
     22 
     23 ===============================================================================
     24 */
     25 
     26 	.text
     27 
     28 /*
     29 -------------------------------------------------------------------------------
     30 Sets the system's IEC/IEEE floating-point rounding mode.  Also disables all
     31 system exception traps.
     32 -------------------------------------------------------------------------------
     33 */
     34 	.align 4
     35 	.global _syst_float_set_rounding_mode
     36 _syst_float_set_rounding_mode:
     37 	movb 4(%esp),%al
     38 	andb $3,%al
     39 	shlw $10,%ax
     40 	orw $63,%ax
     41 	subl $2,%esp
     42 	fnstcw 0(%esp)
     43 	andw $768,0(%esp)
     44 	orw %ax,0(%esp)
     45 	fldcw 0(%esp)
     46 	addl $2,%esp
     47 	ret
     48 
     49 /*
     50 -------------------------------------------------------------------------------
     51 Sets the rounding precision of subsequent extended double-precision
     52 operations.  The `precision' argument should be one of 0, 32, 64, or 80.
     53 If `precision' is 32, the rounding precision is set equivalent to single
     54 precision; else if `precision' is 64, the rounding precision is set
     55 equivalent to double precision; else the rounding precision is set to full
     56 extended double precision.
     57 -------------------------------------------------------------------------------
     58 */
     59 	.align 4
     60 	.global _syst_float_set_rounding_precision
     61 _syst_float_set_rounding_precision:
     62 	movb 4(%esp),%al
     63 	movb $0,%ah
     64 	cmpb $32,%al
     65 	je setRoundingPrecision
     66 	movb $2,%ah
     67 	cmpb $64,%al
     68 	je setRoundingPrecision
     69 	movb $3,%ah
     70 	cmpb $80,%al
     71 	je setRoundingPrecision
     72 	movb $0,%ah
     73 setRoundingPrecision:
     74 	movb $0,%al
     75 	subl $2,%esp
     76 	fnstcw 0(%esp)
     77 	andw $64767,0(%esp)
     78 	orw %ax,0(%esp)
     79 	fldcw 0(%esp)
     80 	addl $2,%esp
     81 	ret
     82 
     83