AT94K ATMEL Corporation, AT94K Datasheet - Page 118

• Manufacturer Part Number: AT94K
• Description: 5K - 40K Gates of At40k FPGA with 8-bit Microcontroller, up to 36K Bytes of SRAM and On-chip JTAG ICE
• Manufacturer: ATMEL Corporation

Comment on
Implementations
118
AT94K Series FPSLIC
All 16-bit x 16-bit = 32-bit functions implemented here start by clearing the R2 register, which
is just used as a “dummy” register with the “add with carry” (ADC) and “subtract with carry”
(SBC) operations. These operations do not alter the contents of the R2 register. If the R2 reg-
ister is not used elsewhere in the code, it is not necessary to clear the R2 register each time
these functions are called, but only once prior to the first call to one of the functions.
fmac16x16_32_method_B
add
fmulsu
adc
adc
adc
fmulsu
sbc
add
adc
adc
fmulsu
sbc
add
adc
adc
ret
clr
fmuls r23, r21
movw
fmul
adc
adc
adc
adc
sbc
add
adc
adc
fmulsu
sbc
add
adc
adc
ret
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
r5:r4,r1:r0
r22, r20
r4, r2
r17, r1
r18, r4
r19, r5
r23, r20
r19, r2
r17, r0
r18, r1
r19, r2
r19, r2
r17, r0
r18, r1
r19, r2
r23, r20
r21, r22
r21, r22
; ( (signed)ah * bl ) << 1
; ( (signed)bh * al ) << 1
; uses two temporary registers (r4,r5), speed/Size
optimized
; but reduces cycles/words by 2
; ( (signed)ah * (signed)bh ) << 1
; ( al * bl ) << 1
; ( (signed)ah * bl ) << 1
; ( (signed)bh * al ) << 1
Rev. 1138F–FPSLI–06/02