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Overview
Comment:Minor change to a comment in encode.c. (CVS 1036)
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SHA1: 3f252b72c9d9ea586161a1b2c5ae297594a1cd4a
User & Date: drh 2003-06-28 16:25:34.000
Context
2003-06-29
16:11
Documentation updates. (CVS 1037) (check-in: ab21de5fdd user: drh tags: trunk)
2003-06-28
16:25
Minor change to a comment in encode.c. (CVS 1036) (check-in: 3f252b72c9 user: drh tags: trunk)
16:20
Fix a bug in the soundex() code. Ticket #367. Add tests for ticket #261 even thought the problem could not be reproduced. (CVS 1035) (check-in: e2ca936fee user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/encode.c.
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*************************************************************************
** This file contains helper routines used to translate binary data into
** a null-terminated string (suitable for use in SQLite) and back again.
** These are convenience routines for use by people who want to store binary
** data in an SQLite database.  The code in this file is not used by any other
** part of the SQLite library.
**
** $Id: encode.c,v 1.8 2003/06/15 23:42:24 drh Exp $
*/
#include <string.h>

/*
** How This Encoder Works
**
** The output is allowed to contain any character except 0x27 (') and








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*************************************************************************
** This file contains helper routines used to translate binary data into
** a null-terminated string (suitable for use in SQLite) and back again.
** These are convenience routines for use by people who want to store binary
** data in an SQLite database.  The code in this file is not used by any other
** part of the SQLite library.
**
** $Id: encode.c,v 1.9 2003/06/28 16:25:34 drh Exp $
*/
#include <string.h>

/*
** How This Encoder Works
**
** The output is allowed to contain any character except 0x27 (') and
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**
** The only tricky part is step (1) - how to compute an offset value to
** minimize the size of the output buffer.  This is accomplished by testing
** all offset values and picking the one that results in the fewest number
** of escapes.  To do that, we first scan the entire input and count the
** number of occurances of each character value in the input.  Suppose
** the number of 0x00 characters is N(0), the number of occurances of 0x01
** is N(1), and so forth up to the number of occurances of 0xff is N(256).
** An offset of 0 is not allowed so we don't have to test it.  The number
** of escapes required for an offset of 1 is N(1)+N(2)+N(40).  The number
** of escapes required for an offset of 2 is N(2)+N(3)+N(41).  And so forth.
** In this way we find the offset that gives the minimum number of escapes,
** and thus minimizes the length of the output string.
*/









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**
** The only tricky part is step (1) - how to compute an offset value to
** minimize the size of the output buffer.  This is accomplished by testing
** all offset values and picking the one that results in the fewest number
** of escapes.  To do that, we first scan the entire input and count the
** number of occurances of each character value in the input.  Suppose
** the number of 0x00 characters is N(0), the number of occurances of 0x01
** is N(1), and so forth up to the number of occurances of 0xff is N(255).
** An offset of 0 is not allowed so we don't have to test it.  The number
** of escapes required for an offset of 1 is N(1)+N(2)+N(40).  The number
** of escapes required for an offset of 2 is N(2)+N(3)+N(41).  And so forth.
** In this way we find the offset that gives the minimum number of escapes,
** and thus minimizes the length of the output string.
*/
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