Texas Instruments MSP50C614 manual Programming Example, C ±± With Assembly Routines

Implementation Details

free(mm2);

free(pp);

}

cmm_func main(int argc,char *argv)

{

int m1[4],m2[4],product[9]; xfer_const(m1,M1,STR_LENGTH(4)); xfer_const(m2,M2,STR_LENGTH(4));

string_multiply(product,STR_LENGTH(9),m1,STR_LENGTH(4),m2,STR_LENGTH(4));

}

5.10.5 Programming Example, C ±± With Assembly Routines

There are several important considerations when using the C±± compiler. The ram allocation must be coordinated so that a location is not accidentally used twice. In assembly this is usually done with IRX files by making each label equal to the location of the previous one, plus whatever storage space is needed. All of the IRX files for a project are then combined in a master IRX file so that the space for each sub file can be allocated. For example ( a master IRX file ):

RAM_SIZE	equ	640
STACK	equ	2 * (RAM_SIZE ± 14)
BEGIN_RAM	equ	0
RESERVED	equ	BEGIN_RAM + 2 * 1
RAMSTART_INT	equ	RESERVED
include º..\inter\inter_ram.irxº
RAMSTART_ASM	equ	RAMEND_INT
include	º. .\asm_ram.irxº

Here the sub files are inter_ram.irx and asm_ram.irx. The allocation for inter_ram.irx begins at memory location 2. This is because the memory location 0 is reserved for use by the C±± compiler. The allocation for asm_ram.irx begins where the allocation ended for inter_ram.irx. More irx files can be chained on in this manner, and all of the allocation is kept organized. When C±± is added to a project, it is important to make sure that the C±± variables are not allocated in locations already used by assembly variables. This is accomplished with a dummy array, bogus, located in the file ram.irx. It is simply an integer array that is included in the C±± program so that it is the first variable allocated. By making its size equivalent to the amount of memory used for assembly variables, the C±± variables that the user defines are allocated in unused memory. It can be set by building the project and finding the location of the last assembly variable. This can then be converted from hexadecimal to decimal and divided by two ( because a C±± int is 16 bits ) to

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