py: Replace naive and teribble hash function with djb2.
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@ -18,9 +18,9 @@ codepoint2name[ord('/')] = 'slash'
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# this must match the equivalent function in qstr.c
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def compute_hash(qstr):
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hash = 0
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hash = 5381
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for char in qstr:
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hash += ord(char)
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hash = (hash * 33) ^ ord(char)
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return hash & 0xffff
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def do_work(infiles):
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@ -18,7 +18,7 @@
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// A qstr is an index into the qstr pool.
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// The data for a qstr contains (hash, length, data).
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// For now we use very simple encoding, just to get the framework correct:
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// - hash is 2 bytes (simply the sum of data bytes)
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// - hash is 2 bytes (see function below)
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// - length is 2 bytes
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// - data follows
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// - \0 terminated (for now, so they can be printed using printf)
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@ -28,10 +28,12 @@
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#define Q_GET_LENGTH(q) ((q)[2] | ((q)[3] << 8))
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#define Q_GET_DATA(q) ((q) + 4)
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// this must match the equivalent function in makeqstrdata.py
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machine_uint_t qstr_compute_hash(const byte *data, uint len) {
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machine_uint_t hash = 0;
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// djb2 algorithm; see http://www.cse.yorku.ca/~oz/hash.html
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machine_uint_t hash = 5381;
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for (const byte *top = data + len; data < top; data++) {
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hash += *data;
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hash = ((hash << 5) + hash) ^ (*data); // hash * 33 ^ data
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}
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return hash & 0xffff;
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}
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