“Copyright (c) 2008 Robert B. Reese, Bryan A. Jones, J. W. Bruce (“AUTHORS”)” All rights reserved. (R. Reese, reese_AT_ece.msstate.edu, Mississippi State University) (B. A. Jones, bjones_AT_ece.msstate.edu, Mississippi State University) (J. W. Bruce, jwbruce_AT_ece.msstate.edu, Mississippi State University)

Permission to use, copy, modify, and distribute this software and its documentation for any purpose, without fee, and without written agreement is hereby granted, provided that the above copyright notice, the following two paragraphs and the authors appear in all copies of this software.

IN NO EVENT SHALL THE “AUTHORS” BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE “AUTHORS” HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

THE “AUTHORS” SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN “AS IS” BASIS, AND THE “AUTHORS” HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.”

Please maintain this header in its entirety when copying/modifying these files.

#include "pic24_all.h"
 

reverse_string.c - Inputs a string, outputs the reverse

This file is used in three MPLAB projects:

• reverse_string.mcp - polled RX, TX I/O
• uartrx_fifo.mcp - interrupt RX, polled TX I/O
• uartrxtx_fifo.mcp - interrupt RX, interrupt TX I/O
• Interrupt RX inChar1() is selected by defining UART1_RX_INTERRUPT macro
• Interrupt TX outChar1() is selected by defining UART1_TX_INTERRUPT macro

These macros are defined in their respective MPLAB projects.

 
void reverseString(char *psz_s1, char *psz_s2) {
  char *psz_s1end;
  if (!(*psz_s1)) {
    *psz_s2 = 0;  //psz_s1 is empty, return.
    return;
  }
  psz_s1end = psz_s1;
  //find end of first string
  while (*psz_s1end) psz_s1end++;
  psz_s1end--;      //backup one to first non-zero byte
  //now copy to S2 in reverse order
  while (psz_s1end != psz_s1) {
    *psz_s2 = *psz_s1end;
    psz_s1end--;
    psz_s2++;
  }
  //copy last byte
  *psz_s2 = *psz_s1end;
  psz_s2++;
  //mark end of string
  *psz_s2 = 0;
}


#define BUFSIZE 63
char  sz_1[BUFSIZE+1];
char  sz_2[BUFSIZE+1];
int main (void) {
  configBasic(HELLO_MSG);
  while (1) {
    inString(sz_1,BUFSIZE);   //get a string from the console
    reverseString(sz_1, sz_2);
    outString(sz_2);          //output the reversed string
    outString("\n");
  }
}