Motorola DSP96002 - Manual (Page 690)

MOTOROLA DSP96002 USER’S MANUAL B-171
; *** f = fraction bits, initially bits in mantissas
; *** l = least significant fraction bit, initially in mantissas
; *** g = guard bit
; *** r = round bit
; *** s - sticky bit
; ***
; ***
; *** Routine Inputs:
; *** d6 - IEEE double extended precision operand 1 (destroyed)
; *** d7 - IEEE double extended precision operand 2 (destroyed)
; ***
; *** Routine Outputs:
; *** d5 - IEEE double extended precision result
; ***
; *** Registers Used:
; *** d0.l - general purpose usage
; *** d0.m - unbiased operand 2 exponent
; *** - unbiased result exponent
; *** d0.h - MSB contains the XOR of the sign bits
; *** d1.l - general purpose usage
; *** d1.m - unbiased operand 1 exponent
; *** - loop index for denormalizing upon underflow.
; *** d1.h - LSB contains the sticky bit
; *** d2.m,l - partial product and intermediate calculations
; *** d3.m,l - partial product and intermediate calculations
; *** d4.m,l - partial product and intermediate calculations
; *** d5.m,l - partial product and intermediate calculations
; ***
; *** NOTES: Currently ignores the FR, P, RP bits.
; *** Assumes that operands are NOT UNnormalized numbers
; *** Code size greatly decreased if "depftst" macro
; *** becomes a routine
; ***
section ieeemult
SR_MASK equ $ffff80c0 ; Status Register Mask, resets cond. codes
EXP_MSK equ $7ff ; Mask for exponent field, 16-bits
EBIAS equ $3ff ; Exponent bias for IEEE double precision
EMAX equ $3ff ; Max exp for normalized double precision val
EMIN equ $fffffc02 ; Min exp for normalized double precision val
EDEN equ $fffffc01 ; Exp for denormalized double precision val
MAX equ $7ff ; Max exp (biased), indicating infs & NaNs
SMSK equ $1ff ; Mask for sticky bit calculation
INUM equ $800 ; Increment for LSB
sdptest ; double precision multiplication subroutine
; ****** Define Program Macros ******
depftst macro op,tmp1,tmp2
; This macro performs the "ftst" function on DEP floating pt vars.
; It sets the NAN,I,N,Z bits in the CCR register appropriately.
;
; op = register name of the form "Dn" containing the floating pt var
; in all 96 bits of the register (not destroyed)