OMAP-L138_16 Datasheet, PDF (13/286 Pages) Texas Instruments – OMAP-L138 C6000 DSP ARM Processor

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OMAP-L138
SPRS586I – JUNE 2009 – REVISED SEPTEMBER 2014
Each C674x .M unit can perform one of the following each clock cycle: one 32 x 32 bit multiply, one 16 x
32 bit multiply, two 16 x 16 bit multiplies, two 16 x 32 bit multiplies, two 16 x 16 bit multiplies with
add/subtract capabilities, four 8 x 8 bit multiplies, four 8 x 8 bit multiplies with add operations, and four
16 x 16 multiplies with add/subtract capabilities (including a complex multiply). There is also support for
Galois field multiplication for 8-bit and 32-bit data. Many communications algorithms such as FFTs and
modems require complex multiplication. The complex multiply (CMPY) instruction takes for 16-bit inputs
and produces a 32-bit real and a 32-bit imaginary output. There are also complex multiplies with rounding
capability that produces one 32-bit packed output that contain 16-bit real and 16-bit imaginary values. The
32 x 32 bit multiply instructions provide the extended precision necessary for high-precision algorithms on
a variety of signed and unsigned 32-bit data types.
The .L or (Arithmetic Logic Unit) now incorporates the ability to do parallel add/subtract operations on a
pair of common inputs. Versions of this instruction exist to work on 32-bit data or on pairs of 16-bit data
performing dual 16-bit add and subtracts in parallel. There are also saturated forms of these instructions.
The C674x core enhances the .S unit in several ways. On the previous cores, dual 16-bit MIN2 and MAX2
comparisons were only available on the .L units. On the C674x core they are also available on the .S unit
which increases the performance of algorithms that do searching and sorting. Finally, to increase data
packing and unpacking throughput, the .S unit allows sustained high performance for the quad 8-bit/16-bit
and dual 16-bit instructions. Unpack instructions prepare 8-bit data for parallel 16-bit operations. Pack
instructions return parallel results to output precision including saturation support.
Other new features include:
• SPLOOP - A small instruction buffer in the CPU that aids in creation of software pipelining loops where
multiple iterations of a loop are executed in parallel. The SPLOOP buffer reduces the code size
associated with software pipelining. Furthermore, loops in the SPLOOP buffer are fully interruptible.
• Compact Instructions - The native instruction size for the C6000 devices is 32 bits. Many common
instructions such as MPY, AND, OR, ADD, and SUB can be expressed as 16 bits if the C674x
compiler can restrict the code to use certain registers in the register file. This compression is
performed by the code generation tools.
• Instruction Set Enhancement - As noted above, there are new instructions such as 32-bit
multiplications, complex multiplications, packing, sorting, bit manipulation, and 32-bit Galois field
multiplication.
• Exceptions Handling - Intended to aid the programmer in isolating bugs. The C674x CPU is able to
detect and respond to exceptions, both from internally detected sources (such as illegal op-codes) and
from system events (such as a watchdog time expiration).
• Privilege - Defines user and supervisor modes of operation, allowing the operating system to give a
basic level of protection to sensitive resources. Local memory is divided into multiple pages, each with
read, write, and execute permissions.
• Time-Stamp Counter - Primarily targeted for Real-Time Operating System (RTOS) robustness, a free-
running time-stamp counter is implemented in the CPU which is not sensitive to system stalls.
For more details on the C674x CPU and its enhancements over the C64x architecture, see the following
documents:
• TMS320C64x/C64x+ DSP CPU and Instruction Set Reference Guide (literature number SPRUFE8)
• TMS320C64x Technical Overview (literature number SPRU395)
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