StarCore SC3400 DSP Subsystem
MSC8144E Reference Manual, Rev. 3
Freescale Semiconductor
1-11
Instruction/data read accesses are performed as follows:
Non-cacheable instructions/data are read from the target memory (for example, M2
memory).
Cacheable instructions/data are read from the ICache/DCache. If they do not reside in the
cache (a miss), they are first fetched directly from the target memory.
There are three write policies when writing data outside the core:
Cacheable write-back. Information is written only to the cache. The modified cache lines
are written to main memory only when they are replaced. The subsequent write-back
buffer is combined with the write-allocate write-miss policy in which the required lines
are loaded to the cache whenever a write-miss occurs.
Cacheable write-through. Both the cache and the higher-level memory are updated during
every write operation. In the StarCore SC3400 DSP subsystem, the write-through buffer is
a non-write allocate buffer. Therefore, a cacheable write-through access does not update
the cache unless there is a hit.
Non-cacheable. The write is direct to memory and is not written to the cache. A hazard
mechanism ensures that read accesses read updated data.
The DSP subsystem supports a Real-Time Operating System (RTOS) as follows:
Virtual-to-physical address translation in the MMU.
Two privilege levels: user and supervisor.
Memory protection.
The embedded programmable interrupt controller (EPIC) handles up to 256 interrupts with 32
priorities, 222 of which are external platform inputs.
1.4.1 StarCore SC3400 DSP Core
The SC3400 core is a flexible, programmable DSP core that handles compute-intensive
communications applications, providing high performance, low power, and high code density. It
is fully binary-backward compatible with the MSC8101, MSC8102, MSC8103, MSC8122,
MSC8126, and the MSC711x family, and it introduces many new features and enhancements.
The SC3400 core includes a data arithmetic logic unit (DALU) that contains four arithmetic logic
units (ALUs). The core also includes an address generation unit (AGU) that contains two address
arithmetic units. The SC3400 efficiently deploys the variable-length execution set (VLES)
execution model, allowing grouping of up to 4 DALU and 2 AGU instructions in a single clock
cycle without sacrificing code size for unused execution slots.
Each ALU has a 16-bit
×
16-bit + 40-bit multiply-accumulate unit, a 40-bit parallel barrel shifter,
and a 40-bit adder/subtractor. Each ALU performs one MAC operation per clock cycle, so a
single core running at 800 MHz/1 GHz can perform up to 3.2/4 GMACS. Each AAU in the AGU
Summary of Contents for MSC8144E
Page 1: ...MSC8144E Reference Manual Quad Core Media Signal Processor MSC8144ERM Rev 3 July 2009 ...
Page 48: ...MSC8144E Reference Manual Rev 3 xlviii Freescale Semiconductor ...
Page 86: ...MSC8144E Reference Manual Rev 3 1 38 Freescale Semiconductor Overview ...
Page 168: ...MSC8144E Reference Manual Rev 3 3 60 Freescale Semiconductor External Signals ...
Page 242: ...MSC8144E Reference Manual Rev 3 5 26 Freescale Semiconductor Reset ...
Page 314: ...MSC8144E Reference Manual Rev 3 8 24 Freescale Semiconductor General Configuration Registers ...
Page 414: ...MSC8144E Reference Manual Rev 3 10 14 Freescale Semiconductor MSC8144E SC3400 DSP Subsystem ...
Page 452: ...MSC8144E Reference Manual Rev 3 11 38 Freescale Semiconductor Internal Memory Subsystem ...
Page 520: ...MSC8144E Reference Manual Rev 3 12 68 Freescale Semiconductor DDR SDRAM Memory Controller ...
Page 1070: ...MSC8144E Reference Manual Rev 3 21 28 Freescale Semiconductor Timers ...