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2011-12-21Fix a bitwise negation assignment issue spotted by Sun StudioLibravatar Ævar Arnfjörð Bjarmason1-1/+1
Change direct and indirect assignments of the bitwise negation of 0 to uint32_t variables to have a "U" suffix. I.e. ~0U instead of ~0. This eliminates warnings under Sun Studio 12 Update 1: "vcs-svn/string_pool.c", line 11: warning: initializer will be sign-extended: -1 (E_INIT_SIGN_EXTEND) "vcs-svn/string_pool.c", line 81: warning: initializer will be sign-extended: -1 (E_INIT_SIGN_EXTEND) "vcs-svn/repo_tree.c", line 112: warning: initializer will be sign-extended: -1 (E_INIT_SIGN_EXTEND) "vcs-svn/repo_tree.c", line 112: warning: initializer will be sign-extended: -1 (E_INIT_SIGN_EXTEND) "test-treap.c", line 34: warning: initializer will be sign-extended: -1 (E_INIT_SIGN_EXTEND) The semantics are still the same as demonstrated by this program: $ cat test.c && make test && ./test #include <stdio.h> #include <stdint.h> int main(void) { uint32_t foo = ~0; uint32_t bar = ~0U; printf("foo = <%u> bar = <%u>\n", foo, bar); return 0; } cc test.c -o test "test.c", line 5: warning: initializer will be sign-extended: -1 foo = <4294967295> bar = <4294967295> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2010-12-07treap: make treap_insert return inserted nodeLibravatar Jonathan Nieder1-3/+8
Suppose I try the following: struct int_node *node = node_pointer(node_alloc(1)); node->n = 5; treap_insert(&root, node); printf("%d\n", node->n); Usually the result will be 5. But since treap_insert draws memory from the node pool, if the caller is unlucky then (1) the node pool will be full and (2) realloc will be forced to move the node pool to find room, so the node address becomes invalid and the result of dereferencing it is undefined. So we ought to use offsets in preference to pointers for references that would remain valid after a call to treap_insert. Tweak the signature to hint at a certain special case: since the inserted node can change address (though not offset), as a convenience teach treap_insert to return its new address. So the motivational example could be fixed by adding "node =". struct int_node *node = node_pointer(node_alloc(1)); node->n = 5; node = treap_insert(&root, node); printf("%d\n", node->n); Based on a true story. Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2010-08-14Add treap implementationLibravatar Jason Evans1-0/+65
Provide macros to generate a type-specific treap implementation and various functions to operate on it. It uses obj_pool.h to store memory nodes in a treap. Previously committed nodes are never removed from the pool; after any *_commit operation, it is assumed (correctly, in the case of svn-fast-export) that someone else must care about them. Treaps provide a memory-efficient binary search tree structure. Insertion/deletion/search are about as about as fast in the average case as red-black trees and the chances of worst-case behavior are vanishingly small, thanks to (pseudo-)randomness. The bad worst-case behavior is a small price to pay, given that treaps are much simpler to implement. >From http://www.canonware.com/download/trp/trp_hash/trp.h [db: Altered to reference nodes by offset from a common base pointer] [db: Bob Jenkins' hashing implementation dropped for Knuth's] [db: Methods unnecessary for search and insert dropped] [rr: Squelched compiler warnings] [db: Added support for immutable treap nodes] [jn: Reintroduced treap_nsearch(); with tests] Signed-off-by: David Barr <david.barr@cordelta.com> Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>