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/* PR 16341 */
#define PART_PRECISION (sizeof (cpp_num_part) * 8)
typedef unsigned int cpp_num_part;
typedef struct cpp_num cpp_num;
struct cpp_num
{
cpp_num_part high;
cpp_num_part low;
int unsignedp; /* True if value should be treated as unsigned. */
int overflow; /* True if the most recent calculation overflowed. */
};
static int
num_positive (cpp_num num, unsigned int precision)
{
if (precision > PART_PRECISION)
{
precision -= PART_PRECISION;
return (num.high & (cpp_num_part) 1 << (precision - 1)) == 0;
}
return (num.low & (cpp_num_part) 1 << (precision - 1)) == 0;
}
static cpp_num
num_trim (cpp_num num, unsigned int precision)
{
if (precision > PART_PRECISION)
{
precision -= PART_PRECISION;
if (precision < PART_PRECISION)
num.high &= ((cpp_num_part) 1 << precision) - 1;
}
else
{
if (precision < PART_PRECISION)
num.low &= ((cpp_num_part) 1 << precision) - 1;
num.high = 0;
}
return num;
}
/* Shift NUM, of width PRECISION, right by N bits. */
static cpp_num
num_rshift (cpp_num num, unsigned int precision, unsigned int n)
{
cpp_num_part sign_mask;
int x = num_positive (num, precision);
if (num.unsignedp || x)
sign_mask = 0;
else
sign_mask = ~(cpp_num_part) 0;
if (n >= precision)
num.high = num.low = sign_mask;
else
{
/* Sign-extend. */
if (precision < PART_PRECISION)
num.high = sign_mask, num.low |= sign_mask << precision;
else if (precision < 2 * PART_PRECISION)
num.high |= sign_mask << (precision - PART_PRECISION);
if (n >= PART_PRECISION)
{
n -= PART_PRECISION;
num.low = num.high;
num.high = sign_mask;
}
if (n)
{
num.low = (num.low >> n) | (num.high << (PART_PRECISION - n));
num.high = (num.high >> n) | (sign_mask << (PART_PRECISION - n));
}
}
num = num_trim (num, precision);
num.overflow = 0;
return num;
}
#define num_zerop(num) ((num.low | num.high) == 0)
#define num_eq(num1, num2) (num1.low == num2.low && num1.high == num2.high)
cpp_num
num_lshift (cpp_num num, unsigned int precision, unsigned int n)
{
if (n >= precision)
{
num.overflow = !num.unsignedp && !num_zerop (num);
num.high = num.low = 0;
}
else
{
cpp_num orig;
unsigned int m = n;
orig = num;
if (m >= PART_PRECISION)
{
m -= PART_PRECISION;
num.high = num.low;
num.low = 0;
}
if (m)
{
num.high = (num.high << m) | (num.low >> (PART_PRECISION - m));
num.low <<= m;
}
num = num_trim (num, precision);
if (num.unsignedp)
num.overflow = 0;
else
{
cpp_num maybe_orig = num_rshift (num, precision, n);
num.overflow = !num_eq (orig, maybe_orig);
}
}
return num;
}
unsigned int precision = 64;
unsigned int n = 16;
cpp_num num = { 0, 3, 0, 0 };
int main()
{
cpp_num res = num_lshift (num, 64, n);
if (res.low != 0x30000)
abort ();
if (res.high != 0)
abort ();
if (res.overflow != 0)
abort ();
exit (0);
}
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