1. Blackfin Syntax Stores, Jumps, Calls and Conditional Jumps
What we already know and have to remember to apply
What we need to learn

2. Assembly code “stub”
Each function written in assembly code has the same general look
The necessary #include files and Section name
Declaration of the function as “global” combined with labels for start and end of function
Setting size of link operation and using LINK instruction to save the return address
Unlink used with JUMP(P0) instruction to cause the function to return “to calling program”
R0 used for return parameter
Required code with Documentation of code
8/5/2019
Timer Control -- Lab.3, Copyright M. Smith, ECE, University of Calgary, Canada

3. Example 1 -- stub code
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Timer Control -- Lab.3, Copyright M. Smith, ECE, University of Calgary, Canada

4. Example 2 – Stub code
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Timer Control -- Lab.3, Copyright M. Smith, ECE, University of Calgary, Canada

5. Store/Write code
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Timer Control -- Lab.3, Copyright M. Smith, ECE, University of Calgary, Canada

6. Store/write error messages
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Timer Control -- Lab.3, Copyright M. Smith, ECE, University of Calgary, Canada

7. Load/read
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Timer Control -- Lab.3, Copyright M. Smith, ECE, University of Calgary, Canada

8. Jump
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Timer Control -- Lab.3, Copyright M. Smith, ECE, University of Calgary, Canada

9. If CC jump If !CC jump
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Timer Control -- Lab.3, Copyright M. Smith, ECE, University of Calgary, Canada

10. Jump predicted taken (bp)
IF CC JUMP WHILE
[--SP] = (R7:0);
// Save to stack
WHILE:
R0 = R1;
R2 = R3;
CC = R1 < R4;
IF CC JUMP WHILE;
R6 = R7;
R5 = R4;
IF CC JUMP WHILE
[--SP] = (R7:0);
// Save to stack
WHILE:
R0 = R1;
R2 = R3;
CC = R1 < R4;
IF CC JUMP WHILE (BP);
R6 = R7;
R5 = R4;
8/5/2019
Timer Control -- Lab.3, Copyright M. Smith, ECE, University of Calgary, Canada

11. Processor fetches instructionS before execution
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Timer Control -- Lab.3, Copyright M. Smith, ECE, University of Calgary, Canada

12. UP to 10 instructions being executed in paraller
Processor fetches 9 new instructions before execution of 1st instruction is complete
UP to 10 instructions being executed in paraller
8/5/2019
Timer Control -- Lab.3, Copyright M. Smith, ECE, University of Calgary, Canada

13. Jump predicted taken (bp)
IF CC JUMP WHILE
[--SP] = (R7:0);
// Save to stack
WHILE:
R0 = R1;
R2 = R3;
CC = R1 < R4;
IF CC JUMP WHILE;
R6 = R7;
R5 = R4;
IF CC JUMP WHILE
[--SP] = (R7:0);
// Save to stack
WHILE:
R0 = R1;
R2 = R3;
CC = R1 < R4;
IF CC JUMP WHILE (bp);
R6 = R7;
R5 = R4;
8/5/2019
Timer Control -- Lab.3, Copyright M. Smith, ECE, University of Calgary, Canada

14. Jump example code
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Timer Control -- Lab.3, Copyright M. Smith, ECE, University of Calgary, Canada

15. Call instruction
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Timer Control -- Lab.3, Copyright M. Smith, ECE, University of Calgary, Canada

16. void ExampleASM(void) {
C++ code
void ExampleASM(void) {
ConvertTempASM(100,200,1); // declared as extern “C” }
Assembly code
8/5/2019
Timer Control -- Lab.3, Copyright M. Smith, ECE, University of Calgary, Canada

17. void Example2ASM(void) {
C++ code
void Example2ASM(void) {
CalculateTemperature(100,200,1); // C++ function }
Assembly code
8/5/2019
Timer Control -- Lab.3, Copyright M. Smith, ECE, University of Calgary, Canada

18. Move Register
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Timer Control -- Lab.3, Copyright M. Smith, ECE, University of Calgary, Canada

19. Conditional move register
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Timer Control -- Lab.3, Copyright M. Smith, ECE, University of Calgary, Canada

20. Practice Exercise Translate in Blackfin Assembly Code
extern “C” unsigned long int WaitTillLow(void);
extern “C” unsigned long int WaitTillHigh(void);
unsigned short int MeasureTimeHigh_ASM(void) {
unsigned long int value;
WaitTillLow( );
WaitTillHigh( );
value = WaitTillLow( );
return value; }
8/5/2019
Timer Control -- Lab.3, Copyright M. Smith, ECE, University of Calgary, Canada

21. Practice Exercise 2 Translate in Blackfin Assembly Code
extern “C” unsigned long int WaitTillLow(void);
extern “C” unsigned long int WaitTillHigh(void);
unsigned long int MeasureTimeHigh_ASM(void) {
unsigned long int value1, value2;
WaitTillLow( );
WaitTillHigh( );
value1 = WaitTillLow( );
value2 = WaitTillLow( );
return (value1 + value2); }
8/5/2019
Timer Control -- Lab.3, Copyright M. Smith, ECE, University of Calgary, Canada

22. Practice Exercise 3 Translate in Blackfin Assembly Code
extern “C” unsigned long int WaitTillLow(void);
extern “C” unsigned long int WaitTillHigh(void);
extern unsigned long int value1;
extern unsigned long int value2;
unsigned long int MeasureTimeHigh_ASM(void) {
WaitTillLow( );
WaitTillHigh( );
value1 = WaitTillLow( );
value2 = WaitTillLow( );
return (value1 + value2); }
8/5/2019
Timer Control -- Lab.3, Copyright M. Smith, ECE, University of Calgary, Canada