Lec10

EEE C415: DIGITAL SIGNAL PROCESSING Lecture 10

Addressing Modes of TMS320C54x

Last Session ¾Addressing Modes of c54x

29 January 2009

EEE C415 / Shikha Tripathi

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Today’s Session • Addressing Modes cont… • Instruction set

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EEE C415 / Shikha Tripathi

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Data Addressing modes 9Immediate Addressing 9Absolute Addressing 9Accumulator Addressing 9Direct Addressing • Indirect Addressing • Memory-Mapped Register Addressing • Stack Addressing

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Indirect Addressing • Uses 8 ARs; AR0-AR7 • Used to step-through sequential locations in mem in fixed-size steps • AR modified by: • Increment / Decrement • Offset • Index • Special modes: 9Circular addressing • Bit-reserved addressing 29 January 2009

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Bit reversed addressing • Enhances the execution speed for FFT algorithm • AR0 specifies one-half the size of FFT (2N-1) where N is integer (2N : size of FFT) • To generate address, add AR0 to any AR which is pointing to a data value in bit reversed fashion. • Carry propagates from left to right

29 January 2009

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Example

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Memory mapped register addressing • Modifies MMRs without affecting DP and SP • In addition to registers any scratch-pad RAM on Data Page 0 can be modified • 2 modes ¾Direct: forces 9 MSBs of Dmem to 0 ¾Indirect: uses 7 LSBs of current AR ¾If AR1 point to MMR & it contains FF25h,then AR1 point to Time Period register(PRD) whose address is 25h (7 LSBs of FF25h).After execution AR1=25h.

• Example ¾LDM MMR ,dst (direct) ¾STM #lk,*arx (indirect) 29 January 2009

EEE C415 / Shikha Tripathi

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Example 1

LDM AR4, A Before execution A

00 0000 1111

AR4 Example 2

FFFF

;Direct After execution A

00 0000 FFFF

AR4

LDM 060h, B

;Direct

Before execution B Data Memory

0060h

29 January 2009

00 0000 0000 1234

FFFF

After execution B 0060h

EEE C415 / Shikha Tripathi

00 0000 1234 1234 9

Example 1

STM #FFFF,IMR

;Direct

Before execution IMR Example 2

After execution

FF01

STM #8765,*Ar7+

IMR ;Indirect

Before execution

29 January 2009

FFFF

After execution

AR0

0000

AR0

8765

AR7

8010

AR7

0011

EEE C415 / Shikha Tripathi

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CPU MMRs (Table 10.3)

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EEE C415 / Shikha Tripathi

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Some MMR addr mode Instructions

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Stack Addressing • System Stack: store PC when interrupt / subroutine • To pass data values. • SP points to the last element stored onto the stack

29 January 2009

EEE C415 / Shikha Tripathi

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PSHD X2 ( )

( ) ( )

• FRAME ??? • INTR ??? • TRAP ??? 29 January 2009

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BUS Operations • • • • •

16-bit read: D bus 16-bit write: E bus 32-bit read: C:D Bus (Msword : Lsword) 32-bit write: ????? For 32-bit data, present address is Msword • Msword even / odd address?? ¾Even:Big Endian ¾Odd: Little endian

29 January 2009

EEE C415 / Shikha Tripathi

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Instruction set • Arithmetic operations • Logical operations • Load and store operations • Program control operations • Special operations

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Arithmetic operation • Absolute value • Addition • Subtraction • Multiplication

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Absolute • ABS src, [dst] • Absolute value of Accumulator • Ex: ABS A, B

• SRC -> DST/ SRC if DST is not specified. • OVM affects the result • C & OV dst flags are affected.

Example

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Addition

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Examples • ADD

*AR2+, 12, A

• ADD

B, -5, A ;(category 9)

• ADD

#2345h, 7, B ;(category 8)

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;(category 3)

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Subtraction

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Example • SUB

*AR1+, 14, A

• SUB

A, -8, B

• SUB

#2345h, 8, A, B

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Explore Others… • ADDC

*+AR2 (5), A

• ADDM

#123Bh, *AR4+

• ADDS

*AR2-, B

• SUBB

*AR1+, B

• SUBS

*AR2-, B

• SUBC

???

– Used for division

29 January 2009

EEE C415 / Shikha Tripathi

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Multiply

MPYR Rounds the result of multiplication by adding 215 to the result & then clearing bits 15-0. 29 January 2009

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Example • MPY • MPY

13, A #FFFEh, A

• MPYR

0, B ; DP=004h

Next Session • Instruction set cont.. • Assembler directives • Simple programs

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EEE C415 / Shikha Tripathi

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Thank You

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