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