93 lines
3.8 KiB
C
93 lines
3.8 KiB
C
/* *****************************************************************************
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* libg1m/buffer.h -- the libg1m buffer interface.
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* Copyright (C) 2017 Thomas "Cakeisalie5" Touhey <thomas@touhey.fr>
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*
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* This file is part of libg1m.
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* libg1m is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 3.0 of the License,
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* or (at your option) any later version.
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*
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* libg1m is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with libg1m; if not, see <http://www.gnu.org/licenses/>.
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*
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* This interface is there so you can use a custom buffer for the library
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* to read. There are two use cases:
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* - you want to read data: the `size` of the element to read should be set,
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* and the `read` callback will be used;
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* - you want to receive data: if the `announce` callback is set, it will be
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* called with the size of the file to write, in order to prepare space for
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* it. If the `announce` callback returns an error, then the file will not
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* be written. If the announcement is successful, then the `write` callback
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* is used.
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*
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* In each case, the `cookie` is sent as the first argument to your callbacks.
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* ************************************************************************** */
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#ifndef LIBG1M_BUFFER_H
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# define LIBG1M_BUFFER_H
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# include <stdlib.h>
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# include <stdint.h>
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/* ************************************************************************** */
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/* General definition */
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/* ************************************************************************** */
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/* The callbacks types... */
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typedef int (*g1m_buffer_read_t)(void*, unsigned char*, size_t);
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typedef int (*g1m_buffer_write_t)(void*, const unsigned char*, size_t);
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typedef int (*g1m_buffer_announce_t)(void*, uint_fast32_t size);
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/* ... and the structure of a buffer. */
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typedef struct {
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void *cookie;
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size_t _offset;
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g1m_buffer_read_t read;
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g1m_buffer_write_t write;
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g1m_buffer_announce_t announce;
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} g1m_buffer_t;
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/* ************************************************************************** */
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/* Memory buffer definition */
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/* ************************************************************************** */
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/* Cookie structure */
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typedef struct {
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const unsigned char *p;
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size_t left;
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} g1m_cursor_t;
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/* Related callbacks and functions */
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int g1m_membuffer_read(void *cookie, unsigned char *dest, size_t size);
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/* ************************************************************************** */
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/* Limited buffer definition */
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/* ************************************************************************** */
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/* Cookie structure */
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typedef struct {
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g1m_buffer_t *buffer;
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size_t left;
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} g1m_limited_t;
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/* Related functions and callbacks */
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int g1m_limbuffer_read(void *cookie, unsigned char *dest, size_t size);
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int g1m_empty_limbuffer(g1m_buffer_t *limbuffer);
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/* ************************************************************************** */
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/* Buffer macros */
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/* ************************************************************************** */
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/* Initialize a memory buffer */
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# define g1m_membuffer(P, SZ) (g1m_buffer_t){ \
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.cookie = (g1m_cursor_t[]){{.p = (P), .left = (SZ)}}, \
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.read = g1m_membuffer_read}
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/* Initialize a limited buffer */
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# define g1m_limbuffer(BUFFER, SZ) (g1m_buffer_t){ \
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.cookie = (g1m_limited_t[]){{.buffer = (BUFFER), .left = (SZ)}}, \
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.read = g1m_limbuffer_read}
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#endif /* LIBG1M_BUFFER_H */
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