Texas Instruments MSP50C6xx manual Programming Example, Cmmfunc bidonint i1,char *i2 is valid, but

Implementation Details

declarations ( or function prototypes) are introduced by the mnemonic cmm_func. We only allow the new style of function declarations /prototypes, where the type of the arguments is declared within the function’s parentheses. For example:

cmm_func bidon(int i1,char *i2) is valid, but:

cmm_func bidon(i1,i2) int i1,char *i2; is invalid.

Note: The exact implementation of the MSP50C6xx stack is as follows:

on CALL:

1)Increment R7

2)Transfer TOS (top of stack) register to *R7

3)Transfer return address to TOS register

on RET:

1)next PC = TOS

2)transfer *R7 to TOS

3)decrement R7

We can freely manipulate R7 before a CALL/Ccc and after a RET to load and unload arguments to and from the stack. The TOS register should never be altered in the body of a function.

5.6.4Programming Example

The following example implements string multiplication (i.e., the multiplication of 2 integer strings). The same source file (with the exception of the first line) can be used for C– – or regular C. In the case of regular C, it has to be compiled and linked with cmm_func.c

#define _CMM /*must be present for C– –compiler ONLY*/ #ifdef _CMM

#else

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <math.h> #include “cmm_back.h” #endif

#include “cmm_func.h”

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