mirror of
https://github.com/SEPPDROID/Digital-Research-Source-Code.git
synced 2025-10-23 08:24:18 +00:00
100 lines
4.8 KiB
ArmAsm
100 lines
4.8 KiB
ArmAsm
ttl ieee format equivalent divide (iefdiv)
|
|
***************************************
|
|
* (c) copyright 1981 by motorola inc. *
|
|
***************************************
|
|
|
|
*************************************************************
|
|
* iefdiv *
|
|
* fast floating point ieee format equivalent divide *
|
|
* *
|
|
* input: d6 - ieee format number divisor (source) *
|
|
* d7 - ieee format number dividend (destination) *
|
|
* *
|
|
* output: d7 - ieee format floating result of register d6 *
|
|
* divided into register d7 *
|
|
* *
|
|
* condition codes: *
|
|
* n - result is negative *
|
|
* z - result is zero *
|
|
* v - result is nan (not-a-number) *
|
|
* c - undefined *
|
|
* x - undefined *
|
|
* *
|
|
* all registers transparent *
|
|
* *
|
|
* maximum stack usage: 24 bytes *
|
|
* *
|
|
* result matrix: arg 2 *
|
|
* others zero infinity nan *
|
|
* arg 1 **************************************** *
|
|
* others * a * b * c * f * *
|
|
* zero * c * d * c * f * *
|
|
* infinity * b * b * d * f * *
|
|
* nan * e * e * e * f * *
|
|
* **************************************** *
|
|
* a = return divide result, overflowing to infinity, *
|
|
* underflowing to zero with proper sign *
|
|
* b = return zero with proper sign *
|
|
* c = return infinity with proper sign *
|
|
* d = return newly created nan (not-a-number) *
|
|
* e = return arg1 (nan) unchanged *
|
|
* f = return arg2 (nan) unchanged *
|
|
* *
|
|
* notes: *
|
|
* 1) see the mc68344 user's guide for a description of *
|
|
* the possible differences between the results *
|
|
* returned here versus those required by the *
|
|
* ieee standard. *
|
|
* *
|
|
*************************************************************
|
|
page
|
|
iefdiv idnt 1,1 ieee format equivalent divide
|
|
|
|
opt pcs
|
|
|
|
xdef iefdiv ieee format equivalent divide
|
|
|
|
xref iefdop double argument conversion routine
|
|
xref iefrtnan create and return nan result routine
|
|
xref ieftieee return and convert back to ieee format
|
|
xref iefrtsze return signed zero with exclusive or signs
|
|
xref iefrtie return infinity with exclusive or signs
|
|
xref ffpdiv reference fast floating point divide routine
|
|
xref ffpcpyrt copyright notice
|
|
|
|
section 9
|
|
|
|
**********************
|
|
* divide entry point *
|
|
**********************
|
|
iefdiv bsr iefdop decode both operands
|
|
bra.s iefnrm +0 branch normalized
|
|
bra.s iefrtinf +2 branch arg2 infinity
|
|
bra.s iefrtzro +4 branch arg1 infinity
|
|
* both are infinity - return a nan +6 both are infinity
|
|
bra iefrtnan return a nan for infinity into infinity
|
|
|
|
* arg1 infinity - return zero with proper sign
|
|
iefrtzro bra iefrtsze return zero with exclusive or'ed sign
|
|
|
|
* arg2 infinity but not arg1 - return infinity with proper sign
|
|
iefrtinf bra iefrtie return infinity with exclusive or'ed sign
|
|
|
|
* normalized numbers - test for zeroes
|
|
iefnrm tst.l d7 ? dividend zero (arg2)
|
|
bne.s ief2nz no, go test divisor for zero
|
|
tst.l d6 ? are both zero
|
|
bne.s iefrtzro no, just dividend - return a zero
|
|
bra iefrtnan return a nan for zero into zero
|
|
|
|
* dividend (arg2) not zero
|
|
ief2nz tst.l d6 ? divisor zero (arg1) but not dividend (arg2)
|
|
beq.s iefrtinf yes, return infinity with proper sign
|
|
|
|
* both arguments non zero and normalized - do the divide
|
|
bsr ffpdiv do fast floating point divide
|
|
beq iefrtzro if result is zero return a proper sign zero
|
|
bra ieftieee convert result back to ieee format
|
|
|
|
end
|