Branches
4-18
ADSP-BF53x/BF56x Blackfin Processor Programming Reference
If subroutines require local, private, and temporary variables beyond the
capabilities of core registers, it is a good idea to place these variables on the
stack as well. The
LINK
instruction takes a parameter that specifies the size
of the stack memory required for this local purpose. The following exam-
ple provides two local 32-bit variables and initializes them to zero when
the routine is entered:
_sub3:
LINK 8;
[--SP] = (R7:0, P5:0);
R7 = 0 (Z);
[FP-4] = R7;
[FP-8] = R7;
...
(R7:0, P5:0) = [SP++];
UNLINK;
RTS;
_sub3.end:
For more information on the
LINK
and
UNLINK
instructions, see
“LINK,
UNLINK” on page 10-17
.
Condition Code Flag
The processor supports a Condition Code (
CC
) flag bit, which is used to
resolve the direction of a branch. This flag may be accessed eight ways:
• A conditional branch is resolved by the value in
CC
.
• A Data register value may be copied into
CC
, and the value in
CC
may be copied to a Data register.
• The
BITTST
instruction accesses the
CC
flag.
Содержание ADSP-BF53x Blackfin
Страница 38: ...Conventions xxxviii ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 134: ...System Reset and Powerup 3 18 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 324: ...Instruction Overview 7 20 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 486: ...Instruction Overview 13 28 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 512: ...Instruction Overview 14 26 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 604: ...Instruction Overview 15 92 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 688: ...Instruction Overview 18 48 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 742: ...Instruction Overview 19 54 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 752: ...Examples 20 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 780: ...Product Identification Register 21 28 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 790: ...ADSP BF535 Flags A 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 800: ...Performance Monitor Registers B 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 994: ...Instructions Listed By Operation Code C 194 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 1042: ...Index I 40 ADSP BF53x BF56x Blackfin Processor Programming Reference...