sdcc-extra/historygraphs/hello-r3ka/hello.c

   1 // Source by Philipp Krause under CC0 1.0
   2
   3 // A "Hello, World!"-Program. We use it to make the board
   4 // output something that can not be mistaken for output
   5 // From a benchmark.
   6
   7 // "Hello, world!" on serial port A @ 38400 baud.
   8
   9 #include <stdint.h>
  10 #include <stdio.h>
  11
  12 #include "r3ka.h"
  13
  14 // _sdcc_external_startup, if present, will be called very early, before initalization
  15 // of global objects. This makes it e.g. useful for dealing with watchdogs that might
  16 // otherwise bite if there are many or large global objects that take a long time to initialize.
  17 #if __SDCC_REVISION >= 13762
  18 unsigned char __sdcc_external_startup(void)
  19 #else
  20 unsigned char _sdcc_external_startup(void)
  21 #endif
  22 {
  23         // Disable watchdog
  24         WDTTR = 0x51;
  25         WDTTR = 0x54;
  26
  27         // normal oscillator, processor and peripheral from main clock, no periodic interrupt
  28         GCSR = 0x08;
  29
  30         return(0);
  31 }
  32
  33 int putchar(int c)
  34 {
  35         while (SASR & 0x04);    // Wait for empty transmitter data register
  36         SADR = c;
  37         return c;
  38 }
  39
  40 void main(void)
  41 {
  42         PCFR = 0x40;    // Use pin PC6 as TXA
  43
  44         TAT4R = 18 - 1; // Value in register is one less than the divider used (e.g. a value of 0 will result in clock division by 1).
  45         TACSR = 0x01;   // Enable timer A
  46
  47         SACR = 0x00;    // No interrupts, 8-bit async mode
  48
  49         for (;;) {
  50                 printf("Hello, World!\n");
  51                 printf ("\x04");
  52         }
  53 }
  54