TMS320F datasheet(206/389 Pages) TI

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MACD

Multiply and Accumulate With Data Move

7-106

Status Bits

Affected by

Affects

PM and OVM

C and OV

Description

The MACD instruction:

- Adds the previous product, shifted as defined by the PM status bits, to the

accumulator. The carry bit is set (C = 1) if the result of the addition gener-

ates a carry and is cleared (C = 0) if it does not generate a carry.

- Loads the TREG with the content of the specified data-memory address.

- Multiplies the data-memory value in the TREG by the contents of the spe-

cified program-memory address.

- Copies the contents of the specified data-memory address to the next

higher data-memory address.

The data- and program-memory locations on the ’C20x may be any nonre-

served, on-chip or off-chip memory locations. If the program memory is block

B0 of on-chip RAM, the CNF bit must be set to 1. If MACD addresses one of

the memory-mapped registers or external memory as a data-memory location,

the effect of the instruction is that of a MAC instruction; the data move will not

occur (see the DMOV instruction description).

When the MACD instruction is repeated, the program-memory address con-

tained in the PC is incremented by 1 during each repetition. This makes it pos-

sible to access a series of operands in program memory. If you use indirect

addressing to specify the data-memory address, a new data-memory address

can be accessed during each repetition. If you use the direct addressing mode,

the specified data-memory address is a constant; it will not be modified during

each repetition.

MACD functions in the same manner as MAC, with the addition of a data move

for on-chip RAM blocks. This feature makes MACD useful for applications

such as convolution and transversal filtering. When used with RPT, MACD be-

comes a single-cycle instruction once the RPT pipeline is started.

Words

Cycles

TMS320F Datasheet(PDF) 206 Page - Texas Instruments