<< Chapter < Page Chapter >> Page >

Cdp indirect : cmem

CDP indirect addressing uses the coefficient data pointer (CDP) to point to data. For accessing data memory/registers, the 16-bit CDP is combined with the 7-bit CDPH to generate a 23-bit address. When concatenated, they are called the XCDP. CDP indirect addressing can also be used to address a specific bit in the accumulators, auxiliary registers, and the temporary registers. Pre- and post-increment and decrement as well as an offset can be used with CDP. CDP can be used as an operand in place of Smem, Lmem, and Cmem.

MOV dbl(Lmem), Cmem MOV dbl(*AR7), *CDP+ ; Values at XAR7 and XAR7 + 1 are read and stored at ; XCDP and XCDP +/- 1 depending on if XCDP was even or odd. ; CDP is incremented by 2 at the end.

Coefficient indirect

Coefficient indirect addressing uses the same address generation process as CDP indirect addressing for data-space accesses. It is useful for instructions that need three memory operands per cycle. It can be used for finite impulse response filters, multiply [accumulate/subtract], and dual multiply [accumulate/subtract].

MPY Xmem, Cmem, ACx :: MPY Ymem, Cmem, ACy ; Cmem must be in a different memory bank from Xmem/Ymem ; for this to work in a single cycle MPY *AR1+, *CDP+, AC0 :: MPY *AR2+, *CDP+, AC1 ; The value at address XAR1 is multiplied by value at ; address XCDP and stored in AC0. At the same time, ; value at XAR2 is multiplied by value at address XCDP ; and stored in AC1. Then CDP is incremented.

Other examples

AMAR *AR3+ ; increments AR3 by 1

The amar (modify auxiliary register) instruction is unusual in the sense that it takes an Smem operand but does nothing with the data pointed to by the ARx register. Its purpose is to perform any of the allowed register modifications discussed abovewithout having to do anything else. This is often handy when you are using an Xmem/Ymem -type instruction but need to do an ARx modification that is only allowed with an Smem -type operand.

Circular addressing

Circular addressing is useful when implementing circular buffers. Circular addressing needs to be enabled for the specific register that is being used to point to memory. This is done by setting the corresponding ARnLC register using BSET ARnLC . When circular addressing is not needed, BCLR ARnLC on the corresponding ARn will disable circular addressing. The circular addressing length will depend on the BK03 , BK47 , and BKC register values. If you are using AR0 through AR3 for the addressing, then BK03 will be used. BKC is the buffer length for CDP . One thing to watch out for is the buffer start address registers (BSA01, BSA23, BSA45, BSA67, BSAC) are added to the auxiliary register or CDP register value whenever circular addressing is used. Be sure to re-initialize the BSA register when implementing multiple filters.

BSET AR1LC ; sets circular addressing for AR1 BCLR AR2LC ; normal addressing for AR2 MOV #13, BK03 ; set buffer length for AR0 through AR3 MACM *AR1+, *AR2+, AC0 ; AC0 = AC0 + ; (value at memory location AR1 + BSA01) x (value at memory location AR2) ; AR1 is incremented with circular addressing, length 13. ; AR2 is simply incremented by 1

Bit-reversed addressing

Bit-reversed addressing is often needed with the fast-fourier transform (FFT). This helps to set up a pointer for the next iteration. Enable bit-reversing on an operand by adding a B after the increment value. When a bit-reverse operand is used, the auxiliary register can not be used for circular addressing. If circuluar address is enabled, the corresponding buffer start address value (BSAxx) will be added to ARn, but ARn is not modified to stay within the circular buffer.

MOV Smem, dst MOV *(AR4 + T0B), T2 ; T2 = value at memory location XAR4 ; AR4 is incremented with T0, using reverse carry propagation.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
Nasa has use it in the 60's, copper as water purification in the moon travel.
nanocopper obvius
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Digital signal processing laboratory (ece 420 55x). OpenStax CNX. Jan 18, 2010 Download for free at http://cnx.org/content/col10397/1.10
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Digital signal processing laboratory (ece 420 55x)' conversation and receive update notifications?