99 lines
2.9 KiB
ReStructuredText
99 lines
2.9 KiB
ReStructuredText
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Character encoding and conversions
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==================================
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libcasio has its own portable character encoding conversion, resembling
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iconv. It supports Unicode transformation formats (UTF-8, UTF-16, UTF-32)
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and CASIO's proprietary character encoding named FONTCHARACTER according to
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the SDK it published in 2006 for the fx-9860G.
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The character conversion utilities are defined in ``<libcasio/char.h>``,
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but as usual, including ``<libcasio.h>`` for everything is recommended.
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Opening and closing a conversion descriptor
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-------------------------------------------
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The conversion descriptor is the main object that will keep track of
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the conversion steps and status. Here are the main functions to manage it:
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.. c:type:: casio_conv_t
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The conversion descriptor type.
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.. c:function:: int casio_open_conv(casio_conv_t *cd, char const *to, \
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char const *from)
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Open the conversion descriptor.
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The ``to`` and ``from`` parameters are the string identifiers of the
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source and destination encodings for the conversion.
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For example, use ``casio_open_conv(&cd, "utf-8", "utf-32")`` to open a
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descriptor that will be able to convert UTF-32 encoded data into UTF-8
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encoded data.
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Converting formats
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------------------
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Once the conversion descriptor is opened, you can use the following
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function:
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.. c:function:: int casio_conv(casio_conv_t cd, \
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char const **in_buffer, size_t *in_left, \
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char **out_buffer, size_t *out_left)
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In the same fashion than iconv, this function is made for being called
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several times, usually because you read from a stream and write to another
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stream — although you can use it to convert data all at once.
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Here is a simple example using two buffers:
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.. code-block:: c
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <libcasio.h>
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int main(void)
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{
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int err = 0; casio_conv_t cd = NULL;
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uint32_t buf0[] = {'H', 'e', 'l', 'l', 'o'};
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size_t buf0_size = 5 * sizeof(uint32_t);
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uint32_t buf1[] = {' ', 'w', 'o', 'r', 'l', 'd', '!'};
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size_t buf1_size = 7 * sizeof(uint32_t);
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char bufdata[30], *buf = &bufdata;
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size_t outsize = 29; /* let space for the end zero */
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/* Open the conversion descriptor. */
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err = casio_open_conv(&cd, "utf-8", "utf-32");
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if (err) {
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fprintf(stderr, "Could not open the conversion desc.: %s",
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casio_strerror(err));
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goto fail;
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}
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/* Convert the first buffer. */
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err = casio_conv(cd, &buf0, &buf0_size, &buf, &outsize);
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if (err) {
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fprintf(stderr, "Could not convert the first buffer: %s",
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casio_strerror(err));
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goto fail;
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}
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/* Convert the second buffer. */
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err = casio_conv(cd, &buf1, &buf1_size, &buf, &outsize);
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if (err) {
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fprintf(stderr, "Could not convert the second buffer: %s",
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casio_strerror(err));
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goto fail;
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}
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/* Print the buffer. */
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*buf = '\0';
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fputs(bufdata, stdout);
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fail:
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/* Close the conversion descriptor. */
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casio_close_conv(cd);
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return (err != 0);
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}
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