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Digital Research
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Sepp J Morris
2020-11-06 18:50:37 +01:00
parent 621ed8ccaf
commit 31738079c4
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CPM OPERATING SYSTEMS/CPM 68K/1.0X SOURCES/v103/libe/iefabs.s Normal file
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ttl ieee format equivalent abs and neg (iefabs/iefneg)
***************************************
* (c) copyright 1981 by motorola inc. *
***************************************
*************************************************************
* iefabs *
* fast floating point ieee format equivalent absolute value*
* *
* input: d7 - ieee format number argument *
* *
* output: d7 - ieee format number absolute value result *
* *
* condition codes: *
* n - cleared *
* z - set if result is zero *
* v - set if result is nan (not-a-number) *
* (occurs only if input argument is nan) *
* c - undefined *
* x - undefined *
* *
* all registers transparent *
* *
* maximum stack used: 24 bytes *
* *
* notes: *
* 1) this routine properly handles all ieee floating *
* point values and number types. *
* 2) if the input argument is a nan (not-a-number) then *
* it will be returned as the result with the "v" bit *
* set in the condition code register. *
* *
*************************************************************
page
iefabs idnt 1,1 ieee format equivalent abs and neg
opt pcs
xdef iefabs ieee format absolute value
xref iefsop single argument conversion routine
xref iefrtod7 return caller's original d7 as result
xref ffpcpyrt copyright notice
section 9
******************************
* absolute value entry point *
******************************
iefabs jsr iefsop direct return to caller if nan encountered
nop +0 normalized return (or zero or denormalized)
* +2 infinity return
* all values may be absolutized by forcing a plus sign on the original value
bclr.b #7,16(sp) clear sign bit of original value
jmp iefrtod7 and return original value altered a wee bit
page
*************************************************************
* iefneg *
* fast floating point ieee format equivalent negate *
* *
* input: d7 - ieee format number argument *
* *
* output: d7 - ieee format number negated result *
* *
* condition codes: *
* n - set if result is negative *
* z - set if result is zero *
* v - set if result is nan (not-a-number) *
* (occurs only if input argument is nan) *
* c - undefined *
* x - undefined *
* *
* all registers transparent *
* *
* maximum stack used: 24 bytes *
* *
* notes: *
* 1) this routine properly handles all ieee floating *
* point values and number types. *
* 2) if the input argument is a nan (not-a-number) then *
* it will be returned as the result with the "v" bit *
* set in the condition code register. *
* *
*************************************************************
page
xdef iefneg ieee format negate
**********************
* negate entry point *
**********************
iefneg jsr iefsop direct return to caller if nan encountered
nop +0 normalized return (or zero or denormalized)
* +6 both infinity return
* all values may be negated by inverting the sign bit of the original value
bchg.b #7,16(sp) negate original sign bit
jmp iefrtod7 and return this modified original register
end