
Enhanced Multiply-Accumulate Unit (EMAC)
4-2
Freescale Semiconductor
Figure 4-1. Multiply-Accumulate Functionality Diagram
4.1.1.1
Introduction to the MAC
The MAC is an extension of the basic multiplier in most microprocessors. It is typically implemented in
hardware within an architecture and supports rapid execution of signal processing algorithms in fewer
cycles than comparable non-MAC architectures. For example, small digital filters can tolerate some
variance in an algorithm’s execution time, but larger, more complicated algorithms such as orthogonal
transforms may have more demanding speed requirements beyond scope of any processor architecture and
may require full DSP implementation.
To balance speed, size, and functionality, the ColdFire MAC is optimized for a small set of operations that
involve multiplication and cumulative additions. Specifically, the multiplier array is optimized for
single-cycle pipelined operations with a possible accumulation after product generation. This functionality
is common in many signal processing applications. The ColdFire core architecture is also modified to
allow an operand to be fetched in parallel with a multiply, increasing overall performance for certain DSP
operations.
Consider a typical filtering operation where the filter is defined as in
.
Eqn. 4-1
Here, the output y(i) is determined by past output values and past input values. This is the general form of
an infinite impulse response (IIR) filter. A finite impulse response (FIR) filter can be obtained by setting
coefficients a(k) to zero. In either case, the operations involved in computing such a filter are multiplies
and product summing. To show this point, reduce
to a simple, four-tap FIR filter, shown in
, in which the accumulated sum is a past data values and coefficients sum.
Eqn. 4-2
X
+/-
Operand Y
Operand X
Shift 0,1,-1
Accumulator(s)
y i
( )
a k
( )
y i
k
–
(
)
k
1
=
N
1
–
∑
b k
( )
x i
k
–
(
)
k
0
=
N
1
–
∑
+
=
y i
( )
b k
( )
x i
k
–
(
)
k
0
=
3
∑
b 0
( )
x i
( )
b 1
( )
x i
1
–
(
)
b 2
( )
x i
2
–
(
)
b 3
( )
x i
3
–
(
)
+
+
+
=
=
MCF5329 Reference Manual, Rev 3
Содержание MCF5329
Страница 106: ...ColdFire Core 3 32 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 126: ...Enhanced Multiply Accumulate Unit EMAC 4 20 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 148: ...Cache 5 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 154: ...Static RAM SRAM 6 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 184: ...Power Management 8 18 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 204: ...Reset Controller Module 10 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 220: ...System Control Module SCM 11 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 228: ...Crossbar Switch XBS 12 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 268: ...General Purpose I O Module 13 40 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 392: ...SDRAM Controller SDRAMC 18 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 436: ...Fast Ethernet Controller FEC 19 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 564: ...Liquid Crystal Display Controller LCDC 22 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 594: ...FlexCAN 23 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 678: ...Pulse Width Modulation PWM Module 26 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 684: ...Watchdog Timer Module 27 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 692: ...Programmable Interrupt Timers PIT0 PIT3 28 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 704: ...DMA Timers DTIM0 DTIM3 29 12 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 720: ...Queued Serial Peripheral Interface QSPI 30 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 754: ...UART Modules 31 34 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 770: ...I2 C Interface 32 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 790: ...Message Digest Hardware Accelerator MDHA 33 20 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 866: ...Debug Module 36 50 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 902: ...Register Memory Map Quick Reference A 26 Freescale Semiconductor MCF5329 Reference Manual Rev 3...