Freescale Semiconductor StarCore SC140 - Manual (Page 471)

DOENn
SC140 DSP Core Reference Manual A-157
DOENn
DO Enable Long Loop (AGU)
DOENn
Description
This instruction initializes the selected loop as a long loop by loading the iteration count into the respective
loop counter and setting the respective loop flag in the SR. After this instruction is executed, the loop
becomes active. There can be other instructions between this instruction and the actual body of the loop. If
the loop is nested, the DOEN instruction must be placed inside the enclosing loop in order to re-activate
the inner loop each iteration. Various programming rules apply concerning the minimum distance between
this instruction and the loop body or other loop instructions.
Status and Conditions that Affect Instruction
None.
Status and Conditions Changed by Instruction
Example
doen2 d0
Operation Assembler Syntax
#u6
→ LCn; 1 → LFn
DOENn #u6 {0
≤ u6 < 64}
#u16
→ LCn; 1 → LFn
DOENn #u16 {0
≤ u16 < 2 16
}
DR
→ LCn; 1 → LFn
DOENn DR
DOENn #u6
Moves an unsigned 6-bit immediate value into the loop counter (LCn) and enables the chosen loop flag.
DOENn #u16
Moves an unsigned 16-bit immediate value into the loop counter (LCn) and enables the chosen loop flag.
DOENn DR
Moves the 32 lower bits of data or address register into the loop counter (LCn) and enables the chosen loop
flag.
Register Address Bit Name Description
SR[30:27] LF[3:0] Sets active loopflag.
Register/Memory Address Before After
D0 $00 0000 000F
LC2 $0000 000F
SR $00E4 0000 $20E4 0000