Skip to content Skip to navigation

Connexions

You are here: Home » Content » FIR Filtering: Basic Assembly Exercise for TI TMS320C54x

Navigation

Lenses

What is a lens?

Definition of a lens

Lenses

A lens is a custom view of Connexions content. You can think of it as a fancy kind of list that will let you see Connexions through the eyes of organizations and people you trust.

What is in a lens?

Lens makers point to Connexions materials (modules and collections), creating a guide that includes their own comments and descriptive tags about the content.

Who can create a lens?

Any individual Connexions member, a community, or a respected organization.

What are tags? tag icon

Tags are descriptors added by lens makers to help label content, attaching a vocabulary that is meaningful in the context of the lens.

This content is ...

Affiliated with (What does "Affiliated with" mean?)

This content is either by members of the organizations listed or about topics related to the organizations listed. Click each link to see a list of all content affiliated with the organization.

Recently Viewed

This feature requires Javascript to be enabled.

Tags

(What is a tag?)

These tags come from the endorsement, affiliation, and other lenses that include this content.

FIR Filtering: Basic Assembly Exercise for TI TMS320C54x

Module by: Douglas L. Jones, Swaroop Appadwedula, Matthew Berry, Mark Haun, Jake Janovetz, Michael Kramer, Dima Moussa, Daniel Sachs, Brian Wade, Jason Laska. E-mail the authors

User rating (How does the rating system work?)
Ratings

Ratings allow you to judge the quality of modules. If other users have ranked the module then its average rating is displayed below. Ratings are calculated on a scale from one star (Poor) to five stars (Excellent).

How to rate a module

Hover over the star that corresponds to the rating you wish to assign. Click on the star to add your rating. Your rating should be based on the quality of the content. You must have an account and be logged in to rate content.

:
(0 ratings)

Summary: You will work through a section of TI TMS320C54x assembly code by hand. The instructions include multiplication of fractional numbers in two's complement representation.

Assembly Exercise

Analyze the following lines of code. Refer to Two's Complement and Fractional Arithmetic for 16-bit Processors, Addressing Modes for TI TMS320C54x, and the Mnemonic Instruction Set [link] manual for help.


	
	1  FIR_len .set    3
	2
	3  ; Assume: 
	4  ;   BK = FIR_len
	5  ;   AR0 = 1
	6  ;   AR2 = 1000h
	7  ;   AR3 = 1004h
	8  ;
	9  ;   FRCT = 1
	10
	11      stl     A,*AR3+%
	12      rptz    A,(FIR_len-1)
	13      mac     *AR2+0%,*AR3+0%,A
	
      

Anything following a ";" is considered a comment. In this case, the comments indicate the contents of the auxiliary registers, the BK register, and the address registers before the execution of the first instruction, stl. The line FIR_len .set 3 defines the name FIR_len as equal to 3. The BK register contains the length of the circular buffer we want to use. The % modifies the increment operator + so that it behaves as a circular buffer. This means that the address registers will be incremented until the (memory-address mod value-in-BK) = 0. When the increment operator + is followed by a 0, it increments by the value specified in register AR0.

Note that any number followed by an "h" or preceded with a 0x represents a hexadecimal value.

Example 1

1000h and 0x1000 both refer to the decimal number 4096.

Assume that the data memory is initialized as follows starting at location 1000h.

Figure 1: Data Memory Assignment (before execution)
Figure 1 (reg1.png)

After familiarizing yourself with the stl, rptz, and mac instructions, step through each line of code and record the values of the accumulator A and auxiliary registers AR2 and AR3 in the spaces provided in Figure 2. Additionally, record the value of the memory contents after all three instructions have been "executed" in the blank data memory table provided in Figure 3.

Figure 2: Execution Results
A AR2 AR3  
00 0000 8000h 1000h 1004h at start of code
      after stl instruction
      after rptz instruction
      after first mac instruction
      after second mac instruction
      after third mac instruction

When working through the exercise, take into account that the accumulator A is a 40-bit register, and that the multiplier is in the fractional arithmetic mode. In this mode, integers on the DSP are interpreted as fractions, and the multiplier will treat them accordingly. This is done by shifting the result of the integer multiplier in the ALU left one bit. (All the arithmetic is fractional in these examples.) Multiplies performed by the ALU (via the mac instruction) produce a result that is twice what you would expect if you just multiplied the two integers together. DSP numerical representation and arithmetic are described further in Two's Complement and Fractional Arithmetic for 16-bit Processors.

Figure 3: Data Memory Assignment (after execution)
Figure 3 (reg2.png)

Content actions

Give Feedback:

E-mail the module authors | Rate module ( How does the rating system work?)

Rating system

Ratings

Ratings allow you to judge the quality of modules. If other users have ranked the module then its average rating is displayed below. Ratings are calculated on a scale from one star (Poor) to five stars (Excellent).

How to rate a module

Hover over the star that corresponds to the rating you wish to assign. Click on the star to add your rating. Your rating should be based on the quality of the content. You must have an account and be logged in to rate content.

(0 ratings)

Download:

Add module to:

My Favorites (?)

'My Favorites' is a special kind of lens which you can use to bookmark modules and collections directly in Connexions. 'My Favorites' can only be seen by you, and collections saved in 'My Favorites' can remember the last module you were on. You need a Connexions account to use 'My Favorites'.

| A lens (?)

Definition of a lens

Lenses

A lens is a custom view of Connexions content. You can think of it as a fancy kind of list that will let you see Connexions through the eyes of organizations and people you trust.

What is in a lens?

Lens makers point to Connexions materials (modules and collections), creating a guide that includes their own comments and descriptive tags about the content.

Who can create a lens?

Any individual Connexions member, a community, or a respected organization.

What are tags? tag icon

Tags are descriptors added by lens makers to help label content, attaching a vocabulary that is meaningful in the context of the lens.

| External bookmarks