Using The .Call Directive In Linear Assembly - Texas Instruments TMS320C6000 Programmer's Manual

Linear Assembly Considerations
8.3.1.1 Function Calls and ADDKPC in Linear Assembly
Example 8–22. Using the .call Directive in Linear Assembly
.data
hello .string "Hello World", 0
.text
.global _puts
.global _main
_main .cproc
.reg
loop:
MVKL
MVKH
.call
B
.endproc
Example 8–23. Compiler Output Using ADDKPC
loop:
; .call _puts(pointer)
B .S1
MVKL .S1
ADDKPC .S2
MVKH .S1
RL0: ; CALL OCCURS
8-48
The 'C64x provides a new instruction, ADDKPC , which is designed to reduce
codesize when making function calls. This new instruction is not directly ac-
cessible from Linear Assembly. However, Linear Assembly provides the func-
tion call directive, .call, and this directive makes use of ADDKPC. The .call di-
rective is explained in detail in the TMS320C6000 Optimizing C/C++ Compiler
User's Guide .
Example 8–22 illustrates a simple use of the .call directive. The Assembly Op-
timizer issues an ADDKPC as part of the function call sequence for this .call,
as shown in the compiler output in Example 8–23.
pointer
hello, pointer
hello, pointer
_puts(pointer)
loop
; Print the string "Hello World".
_puts ; |15|
hello,A4 ; |12|
RL0,B3,2 ; |15|
hello,A4 ; |13|
; |15|
; Generate a 32–bit pointer to the
; phrase "Hello World".
; Print the string "Hello World".
; Keep printing it.
Generate a 32–bit pointer to the
phrase "Hello World".