Central Processing Unit
2-6
2.2.3
Multiplier
The on-chip multiplier performs 16-bit
×
16-bit 2s-complement multiplication
with a 32-bit result. In conjunction with the multiplier, the ’C2xx uses the 16-bit
temporary register (TREG) and the 32-bit product register (PREG). The TREG
always supplies one of the values to be multiplied. The PREG receives the re-
sult of each multiplication.
Using the multiplier, TREG, and PREG, the ’C2xx efficiently performs funda-
mental DSP operations such as convolution, correlation, and filtering. The ef-
fective execution time of each multiplication instruction can be as short as one
CPU cycle.
2.2.4
Auxiliary Register Arithmetic Unit (ARAU) and Auxiliary Registers
The ARAU generates data memory addresses when an instruction uses indi-
rect addressing (see Chapter 6,
Addressing Modes) to access data memory.
The ARAU is supported by eight auxiliary registers (AR0 through AR7), each
of which can be loaded with a 16-bit value from data memory or directly from
an instruction word. Each auxiliary register value can also be stored to data
memory. The auxiliary registers are referenced by a 3-bit auxiliary register
pointer (ARP) embedded in status register ST0.
