at94k40al ATMEL Corporation, at94k40al Datasheet - Page 127

• Manufacturer Part Number: at94k40al
• Description: At94kal Series Field Programmable System Level Integrated Circuit
• Manufacturer: ATMEL Corporation

4.28.7.6
1138I–FPSLI–1/08
fmac16x16_32
Description
Usage
Statistics
Signed fractional multiply-accumulate of two 16-bit numbers with a 32-bit result.
R19:R18:R17:R16 += (R23:R22 • R21:R20) << 1
Cycles: 25 + ret
Words: 21 + ret
Register usage: R0 to R2 and R16 to R23 (11 registers)
fmac16x16_32:
fmac16x16_32_method_B
speed/Size
clr
fmuls r23, r21
add
adc
fmul
adc
adc
add
adc
adc
adc
fmulsu
sbc
add
adc
adc
fmulsu
sbc
add
adc
adc
ret
clr
r2
r18, r0
r19, r1
r22, r20
r18, r2
r19, r2
r16, r0
r17, r1
r18, r2
r19, r2
r19, r2
r17, r0
r18, r1
r19, r2
r19, r2
r17, r0
r18, r1
r19, r2
r2
r23, r20
r21, r22
; Register usage optimized
; ( (signed)ah * (signed)bh ) << 1
; ( al * bl ) << 1
optimized
; but reduces cycles/words by 2
; ( (signed)ah * bl ) << 1
; ( (signed)bh * al ) << 1
; uses two temporary registers (r4,r5),
AT94KAL Series FPSLIC
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