Wondering how printf("") might cause problems, I looked at the executed
code in printf_large. Basically it should just do a read from the
pointer, see that we are at the end of the string and return.
So I found the read from a pointer is the problem. Placing a read from a
generic pointer in main() causes the same issues as the call to printf()
(as long a printf() is linked into the binary). The attached example
code printf "Hello " again and again, but never "World!".
Philipp
#include <stdio.h>
__sfr __at(0xe1) XBR0;
__sfr __at(0xe2) XBR1;
__sfr __at(0xa4) P0MDOUT;
__sfr __at(0xd9) PCA0MD;
__sfr __at(0x88) TCON;
__sfr __at(0x89) TMOD;
__sfr __at(0x8b) TL1;
__sfr __at(0x8d) TH1;
__sfr __at(0x98) SCON0;
__sfr __at(0x99) SBUF0;
__sfr __at(0xef) SRTSRC;
int putchar(int c)
{
while(!(SCON0 & 0x02));
SCON0 &= ~0x02;
SBUF0 = c;
return (c);
}
unsigned char _sdcc_external_startup(void)
{
PCA0MD = 0; // Disable watchdog timer
return 0; // perform normal initialization
}
char c;
char *gptr;
void main(void)
{
unsigned long int i = 0;
// Initialize I/O pins
P0MDOUT = 0x10; // Set port P0.4 (Uart tx) to push-pull
XBR0 = 0x01; // UART0 on P0.4 and P0.5
XBR1 = 0x40; // Enable push/pull for Tx
// Configure UART for 1200 baud, 8 data bits, 1 stop bit.
TMOD = 0x20;
TH1 = 150;
TCON |= 0x40;
SCON0 = 0x42;
for(;;)
{
putchar('H');
putchar('e');
putchar('l');
putchar('l');
putchar('o');
putchar(' ');
for(i = 0; i < 50000; i++); // Sleep
c = 'W';
gptr = &c;
putchar(*gptr);
for(i = 0; i < 50000; i++); // Sleep
putchar('o');
putchar('r');
putchar('l');
putchar('d');
printf("!");
for(;;);
}
}
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