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#include <stdlib.h>
#include <string.h>
#include "../core/index.h"
#include "sequence.h"
/*
* Bypass rendundant ZoO_START_OF_SEQUENCE_ID at the start of a sequence.
*/
/*@
requires
(
\valid(sequence+ (0 .. sequence_length))
|| (sequence_length == 0)
);
requires \separated(sequence, sequence_offset);
assigns (*sequence_offset);
ensures (*sequence_offset < sequence_length);
ensures
(
(*sequence_offset == 0)
|| (sequence[0 .. *sequence_offset] == ZoO_START_OF_SEQUENCE_ID)
);
ensures
(
(*sequence_offset == sequence_length)
|| (sequence[*sequence_offset + 1] != ZoO_START_OF_SEQUENCE_ID)
);
@*/
static void bypass_redundant_sos
(
const ZoO_index sequence [const restrict],
const size_t sequence_length,
size_t sequence_offset [const restrict static 1]
)
{
ZoO_index i;
*sequence_offset = 0;
/*@
loop invariant 0 <= i <= sequence_length;
loop invariant (*sequence_offset <= i);
loop invariant
(
(*sequence_offset == 0)
|| (sequence[*sequence_offset] == ZoO_START_OF_SEQUENCE_ID)
);
loop invariant
(
(i == 0) || (sequence[0 .. (i - 1)] == ZoO_START_OF_SEQUENCE_ID)
);
loop assigns i, *sequence_offset;
loop variant (sequence_length - i);
@*/
for (i = 0; i < sequence_length; ++i)
{
if (sequence[i] != ZoO_START_OF_SEQUENCE_ID)
{
return;
}
else if (sequence[i] == ZoO_START_OF_SEQUENCE_ID)
{
*sequence_offset = i;
}
}
}
/* See "sequence.h" */
/*@
\requires
(
\valid(sequence_a+ (0 .. sequence_a_length))
|| (sequence_a_length == 0)
);
\requires
(
\valid(sequence_b+ (0 .. sequence_b_length))
|| (sequence_b_length == 0)
);
assigns \result;
@*/
int ZoO_sequence_cmp
(
const ZoO_index sequence_a [const],
size_t sequence_a_length,
const ZoO_index sequence_b [const],
size_t sequence_b_length
)
{
size_t min_length, a, b;
size_t a_offset, b_offset;
size_t i;
/*@ ghost size_t actual_a_length, actual_b_length; @*/
bypass_redundant_sos(sequence_a, sequence_a_length, &a_offset);
bypass_redundant_sos(sequence_b, sequence_b_length, &b_offset);
/*@ ghost actual_a_length = sequence_a_length; @*/
/*@ ghost actual_b_length = sequence_b_length; @*/
/*@ assert (a_offset <= sequence_a_length); @*/
sequence_a_length -= a_offset;
/*@ assert (b_offset <= sequence_b_length); @*/
sequence_b_length -= b_offset;
if (sequence_a_length < sequence_b_length)
{
min_length = sequence_a_length;
}
else
{
min_length = sequence_b_length;
}
/*@ assert (min_length <= sequence_a_length); @*/
/*@ assert (min_length <= sequence_b_length); @*/
/*@ assert (min_length + a_offset <= actual_a_length); @*/
/*@ assert (min_length + b_offset <= actual_b_length); @*/
/*@
loop invariant 0 <= i <= min_length;
loop assigns i;
loop variant (min_length - i);
@*/
for (i = 0; i < min_length; ++i)
{
/*@ assert ((i + a_offset) < actual_a_length); @*/
a = sequence_a[i + a_offset];
/*@ assert ((i + b_offset) < actual_b_length); @*/
b = sequence_b[i + b_offset];
if (a < b)
{
return -1;
}
else if (b > a)
{
return 1;
}
else if ((a == ZoO_END_OF_SEQUENCE_ID) && (b == ZoO_END_OF_SEQUENCE_ID))
{
return 0;
}
}
if (sequence_a_length > sequence_b_length)
{
return 1;
}
else if (sequence_a_length < sequence_b_length)
{
return -1;
}
else
{
return 0;
}
}
|
