2. Reálná čísla a paměti SRAM a DRAM

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Programové ukázky

Program add.c:

#include <stdio.h>

int main() {
  unsigned char a=150u, b=120u, c;
  unsigned short as=40000u, bs=30000u, cs;
  char ac=-100, bc=-80, cc;
  short sas=-20000, sbs=-14000, scs;

  c = a+b; cs=as+bs; cc=ac+bc; scs=sas+sbs;
  printf("c=%u cs=%u cc=%i scs=%i\n", c, cs, cc, scs);
}

Program add_test_overflow.c:

#include <stdio.h>

int main() {
  unsigned char a=150u, b=120u, c;
  unsigned short as=40000u, bs=30000u, cs;
  char ac=-100, bc=-80, cc;
  short sas=-20000, sbs=-14000, scs;

  if ( __builtin_add_overflow(a,b,&c)) {
      printf("Overflow detected a+b\n");
  } else {
      printf("c=%u\n", c);
  }
  a=120u;
  if ( __builtin_add_overflow(a,b,&c)) {
      printf("Overflow detected a+b\n");
  } else {
      printf("c=%u\n", c);
  }
  if ( __builtin_add_overflow(as,bs,&cs)) {
      printf("Overflow detected as+bs\n");
  } else {
      printf("cs=%u\n", cs);
  }
  as=33333u;
  if ( __builtin_add_overflow(as,bs,&cs)) {
      printf("Overflow detected as+bs\n");
  } else {
      printf("cs=%u\n", cs);
  }
  
  if ( __builtin_add_overflow(ac,bc,&cc)) {
      printf("Overflow detected ac+bc\n");
  } else {
      printf("cc=%i\n", cc);
  }
  ac=-40;
  if ( __builtin_add_overflow(ac,bc,&cc)) {
      printf("Overflow detected ac+bc\n");
  } else {
      printf("cc=%i\n", cc);
  }
  if ( __builtin_add_overflow(sas,sbs,&scs)) {
      printf("Overflow detected sas+sbs\n");
  } else {
      printf("scs=%i\n", scs);
  }
  sas=-12000;
  if ( __builtin_add_overflow(sas,sbs,&scs)) {
      printf("Overflow detected sas+sbs\n");
  } else {
      printf("scs=%i\n", scs);
  }
}

Program store.c:

#include <stdio.h>
int main() {
  unsigned char p[] = {0,0,0xa0,0xbf};
  printf("%i = %u = %f\n", *(int*)p, *(unsigned int *)p, *(float *)p);
}

Program little.c:

#include <stdio.h>

int main() {
  unsigned char p[] = {0,0,0xa0,0xbf};
  *(int*)p=10;
  printf("%02x,%02x,%02x,%02x\n", p[0],p[1],p[2],p[3]);
}

Odkazy na další literaturu

courses/b35apo/lectures/02/start.txt · Last modified: 2024/02/02 18:41 (external edit)