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qstr, objstr: Make sure that valid hash != 0, treat 0 as "not computed".

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This feature was proposed with initial hashing RFC, and is prerequisite for
seamless static str object definition.
This commit is contained in:
Paul Sokolovsky 2014-04-14 01:43:01 +03:00
parent 14de114ba8
commit 59e269cfec
2 changed files with 8 additions and 2 deletions
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3
py/objstr.c
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@ -1463,7 +1463,8 @@ bool mp_obj_str_equal(mp_obj_t s1, mp_obj_t s2) {
} else {
GET_STR_HASH(s1, h1);
GET_STR_HASH(s2, h2);
if (h1 != h2) {
// If any of hashes is 0, it means it's not valid
if (h1 != 0 && h2 != 0 && h1 != h2) {
return false;
}
GET_STR_DATA_LEN(s1, d1, l1);

7
py/qstr.c
View File

@ -35,7 +35,12 @@ machine_uint_t qstr_compute_hash(const byte *data, uint len) {
for (const byte *top = data + len; data < top; data++) {
hash = ((hash << 5) + hash) ^ (*data); // hash * 33 ^ data
}
return hash & 0xffff;
hash &= 0xffff;
// Make sure that valid hash is never zero, zero means "hash not computed"
if (hash == 0) {
hash++;
}
return hash;
}
typedef struct _qstr_pool_t {