TMS320F datasheet(202/389 Pages) TI

202 / 389 page

MAC

Multiply and Accumulate

7-102

Description

The MAC 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.

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.

When the MAC 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.

MAC is useful for long sum-of-products operations because, when repeated,

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

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TMS320F Datasheet(PDF) 202 Page - Texas Instruments