UPD77115 View Datasheet(PDF) - NEC => Renesas Technology

Part Name

Description

Manufacturer

UPD77115

16-BIT FIXED-POINT DIGITAL SIGNAL PROCESSOR

NEC => Renesas Technology 

µPD77115, 77115A

2.2 Arithmetic Unit

This unit performs multiplication, addition, logical operations, and shift, and consists of a 40-bit multiply accumulator,

40-bit data ALU, 40-bit barrel shifter, and eight 40-bit general-purpose registers.

2.2.1 General-purpose registers (R0 to R7)

These eight 40-bit registers are used to input/output data for arithmetic operations, and load or store data from/to

data memory.

A general-purpose register (R0 to R7) is made up of three parts: R0L to R7L (bits 15 to 0), R0H to R7H (bits 31 to

16), and R0E to R7E (bits 39 to 32). Depending on the type of operation, RnL, RnH, and RnE are used as one

register or in different combinations.

2.2.2 Multiply accumulator (MAC)

The MAC multiplies two 16-bit values, and adds or subtracts the multiplication result from one 40-bit value, and

outputs a 40-bit value.

The MAC is provided with a shifter (MSFT: MAC ShiFTer) at the stage preceding the input stage. This shifter can

arithmetically shift the 40-bit value to be added to or subtracted from the multiplication result 1 or 16 bits to the right .

2.2.3 Arithmetic logic unit (ALU)

This unit inputs one or two 40-bit values, executes an arithmetic or logical operation, and outputs a 40-bit value.

2.2.4 Barrel shifter (BSFT: Barrel ShiFTer)

The barrel shifter inputs a 40-bit value, shifts it to the left or right by any number of bits, and outputs a 40-bit value.

The data may be arithmetically shifted to the right shifted to the right, in which case the data is sign-extended, or

logically shifted to the right, in which case 0 is inserted from the MSB.

16

Data Sheet U14867EJ5V0DS

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