// Test a C23-compliant implementation of deserialization of a 16-bit
// signed value.  Tested on amd64 (char is signed char) and ARM EABI5
// emulated with QEMU (char is unsigned char).
#include <stdio.h>

typedef struct {
  char hh, lh;
  int expected;
} testcase;

testcase cases[] = {
  { 0, 0, 0 },
  { 0, 1, 1 },
  { 1, 0, 256 },
  { 255, 255, -1 },
  { 128, 0, -32768 },
  { 132, 245, -31499 },
  { 80, 224, 20704 },
};

int decode(char hh, char lh)
{
  return (unsigned char)lh | ((int)(signed char)hh << 8);
}    

int main()
{
  int failures = 0;
  for (int i = 0; i != sizeof cases / sizeof(testcase); i++) {
    testcase t = cases[i];
    int result = decode(t.hh, t.lh);
    if (result != t.expected) {
      failures++;
      fprintf(stderr, "decode(%d, %d) == %d rather than expected %d\n",
              t.hh, t.lh, result, t.expected);
    }
  }
  return failures;
}