
Freescale Semiconductor
4-1
Chapter 4
Enhanced Multiply-Accumulate Unit (EMAC)
4.1
Introduction
This chapter describes the functionality, microarchitecture, and performance of the enhanced
multiply-accumulate (EMAC) unit in the ColdFire family of processors.
4.1.1
Overview
The EMAC design provides a set of DSP operations that can improve the performance of embedded code
while supporting the integer multiply instructions of the baseline ColdFire architecture.
The MAC provides functionality in three related areas:
1. Signed and unsigned integer multiplication
2. Multiply-accumulate operations supporting signed and unsigned integer operands as well as
signed, fixed-point, and fractional operands
3. Miscellaneous register operations
The ColdFire family supports two MAC implementations with different performance levels and
capabilities. The original MAC features a three-stage execution pipeline optimized for 16-bit operands,
with a 16x16 multiply array and a single 32-bit accumulator. The EMAC features a four-stage pipeline
optimized for 32-bit operands, with a fully pipelined 32
×
32 multiply array and four 48-bit accumulators.
The first ColdFire MAC supported signed and unsigned integer operands and was optimized for 16x16
operations, such as those found in applications including servo control and image compression. As
ColdFire-based systems proliferated, the desire for more precision on input operands increased. The result
was an improved ColdFire MAC with user-programmable control to optionally enable use of fractional
input operands.
EMAC improvements target three primary areas:
•
Improved performance of 32
×
32 multiply operation.
•
Addition of three more accumulators to minimize MAC pipeline stalls caused by exchanges
between the accumulator and the pipeline’s general-purpose registers
•
A 48-bit accumulation data path to allow a 40-bit product, plus 8 extension bits increase the
dynamic number range when implementing signal processing algorithms
The three areas of functionality are addressed in detail in following sections. The logic required to support
this functionality is contained in a MAC module (
).
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...