A Block Floating Point Implementation on the TMS320C54x DSP

SPRA610
ST B,*Q+0% ; DATA
add #N,a
stlm a, ar3 ; ar3 –> DATA+(offset=N)
stm #cos,ar4 ; start of cosine in stage ’stg’
stm #sin,ar5 ; start of sine in stage ’stg’
buttfly N/2
; execute N/2 butterflies
.endm
;*********************************************************************
; macro : stdmacro
;–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––
stdmacro .macro stage,l1,l2,idx,sin,cos
; .global STAGE:stage:,end
STAGE:stage: .set $
ld #0, ASM ; Introduced by AC 06/06/99 to bypass autoscaling
; and scale only when required within the file
; cfft64_2.asm
ld *sp(DATA),a
stl a,ar2 ; ar2 –> DATA
add #idx,a ; ar3 –> DATA+(offset=idx)
stlm a,ar3
stm #l1–1,ar1 ; outer loop counter
stm #cos,ar6 ; start of cosine in stage ’stg’
stm #sin,ar7 ; start of sine in stage ’stg’
loop mvmm ar6,ar4
mvmm ar7,ar5
buttfly l2
; start of cosine in stage ’stg’
; start of sine in stage ’stg’
; execute l2 butterflies
mar *+ar2(idx)
banzd loop,*ar1–
32 A <strong>Block</strong> <strong>Floating</strong> <strong>Point</strong> <strong>Implementation</strong> on the TMS320C54x DSP