41 lines
1.3 KiB
C
41 lines
1.3 KiB
C
|
/* sort.h
|
||
|
|
* Copyright 1984-2017 Cisco Systems, Inc.
|
||
|
|
*
|
||
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
||
|
|
* you may not use this file except in compliance with the License.
|
||
|
|
* You may obtain a copy of the License at
|
||
|
|
*
|
||
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
||
|
|
*
|
||
|
|
* Unless required by applicable law or agreed to in writing, software
|
||
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
||
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||
|
|
* See the License for the specific language governing permissions and
|
||
|
|
* limitations under the License.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#define mkmergesort(sort, merge, type, nil, lt, cdr)\
|
||
|
|
type sort(type ls, uptr len) {\
|
||
|
|
if (len == 1) {\
|
||
|
|
cdr(ls) = nil;\
|
||
|
|
return ls;\
|
||
|
|
} else {\
|
||
|
|
uptr head_len, i; type tail;\
|
||
|
|
head_len = len >> 1;\
|
||
|
|
for (tail = ls, i = head_len; i != 0; i -= 1) tail = cdr(tail);\
|
||
|
|
return merge(sort(ls, head_len), sort(tail, len - head_len));\
|
||
|
|
}\
|
||
|
|
}\
|
||
|
|
type merge(type ls1, type ls2) {\
|
||
|
|
type p; type *pp = &p;\
|
||
|
|
for (;;) {\
|
||
|
|
if (ls1 == nil) { *pp = ls2; break; }\
|
||
|
|
if (ls2 == nil) { *pp = ls1; break; }\
|
||
|
|
if (lt(ls2, ls1))\
|
||
|
|
{ *pp = ls2; pp = &cdr(ls2); ls2 = cdr(ls2); }\
|
||
|
|
else\
|
||
|
|
{ *pp = ls1; pp = &cdr(ls1); ls1 = cdr(ls1); }\
|
||
|
|
}\
|
||
|
|
return p;\
|
||
|
|
}
|