Texas Instruments TMS320C3x - Manual (Page 188)

Repeat Modes
7-4
Example 7–1. Repeat-Mode Control Algorithm
if RM == 1 ; If in repeat mode (RPTB or RPTS)
if S == 1 ; If RPTS
if first time through ; If this is the first fetch
fetch instruction from memory ; Fetch instruction from memory
else ; If not the first fetch
fetch instruction from IR ; Fetch instruction from IR
RC – 1
→
RC ; Decrement RC
if RC < 0 ; If RC is negative
; Repeat single mode completed
0
→
ST(RM) ; Turn off repeat-mode bit
0
→
S ; Clear S
PC + 1
→
PC ; Increment PC
else if S == 0 ; If RPTB
fetch instruction from memory ; Fetch instruction from memory
if PC == RE ; If this is the end of the block
RC – 1
→
RC ; Decrement RC
if RC
≥
0 ; If RC is not negative
RS
→
PC ; Set PC to start of block
else if RC < 0 ; If RC is negative
0
→
ST(RM) ; Turn off repeat mode bits
0
→
S ; Clear S
PC + 1
→
PC ; Increment PC
7.1.3 RPTB Instruction
The RPTB instruction repeats a block of code a specified number of times.
The number of times to repeat the block is the RC (repeat count) register value
plus 1. Because the execution of RPTB does not load the RC, you must load this
register yourself. The RC register must be loaded before the RPTB instruction is
executed. A typical setup of the block repeat operation is shown in Example 7–2.
Example 7–2. RPTB Operation
LDI 15,RC ; Load repeat counter with 15
RPTB ENDLOOP ; Execute the block of code
STLOOP ; from STLOOP to ENDLOOP 16
; times
.
.
.
ENDLOOP