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OS/2 Shareware BBS: 10 Tools
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libsrc
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longlong
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subdi3.c
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C/C++ Source or Header
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1992-02-22
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738b
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48 lines
#include "longlong.h"
static int bsub ();
long long
__subdi3 (u, v)
long long u, v;
{
long a[2], b[2], c[2];
long_long w;
long_long uu, vv;
uu.ll = u;
vv.ll = v;
a[HIGH] = uu.s.high;
a[LOW] = uu.s.low;
b[HIGH] = vv.s.high;
b[LOW] = vv.s.low;
bsub (a, b, c, sizeof c);
w.s.high = c[HIGH];
w.s.low = c[LOW];
return w.ll;
}
static int
bsub (a, b, c, n)
unsigned short *a, *b, *c;
size_t n;
{
signed long acc;
int i;
n /= sizeof *c;
acc = 0;
for (i = little_end (n); is_not_msd (i, n); i = next_msd (i))
{
/* Widen before subtracting to avoid loss of high bits. */
acc += (long) a[i] - b[i];
c[i] = acc & low16;
acc = acc >> 16;
}
return acc;
}