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67 lines
2.8 KiB
C
67 lines
2.8 KiB
C
/* buffer.h
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Definitions for the object management API protocol buffering... */
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/*
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* Copyright (c) 1996-1999 Internet Software Consortium.
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* Use is subject to license terms which appear in the file named
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* ISC-LICENSE that should have accompanied this file when you
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* received it. If a file named ISC-LICENSE did not accompany this
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* file, or you are not sure the one you have is correct, you may
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* obtain an applicable copy of the license at:
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*
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* http://www.isc.org/isc-license-1.0.html.
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*
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* This file is part of the ISC DHCP distribution. The documentation
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* associated with this file is listed in the file DOCUMENTATION,
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* included in the top-level directory of this release.
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*
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* Support and other services are available for ISC products - see
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* http://www.isc.org for more information.
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*/
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/* OMAPI buffers are ring buffers, which means that the beginning of the
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buffer and the end of the buffer chase each other around. As long as
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the tail never catches up to the head, there's room in the buffer for
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data.
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- If the tail and the head are equal, the buffer is empty.
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- If the tail is less than the head, the contents of the buffer
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are the bytes from the head to the end of buffer, and in addition,
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the bytes between the beginning of the buffer and the tail, not
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including the byte addressed by the tail.
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- If the tail is greater than the head, then the buffer contains
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valid bytes starting with the byte addressed by the head, and
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ending with the byte before the byte addressed by the tail.
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There will always be at least one byte of waste, because the tail can't
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increase so that it's equal to the head (that would represent an empty
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buffer. */
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#define OMAPI_BUF_SIZE 4048
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typedef struct _omapi_buffer {
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struct _omapi_buffer *next; /* Buffers can be chained. */
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u_int32_t refcnt; /* Buffers are reference counted. */
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u_int16_t head, tail; /* Buffers are organized in a ring. */
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char buf [OMAPI_BUF_SIZE]; /* The actual buffer is included in
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the buffer data structure. */
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} omapi_buffer_t;
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#define BUFFER_BYTES_AVAIL(x) \
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(((x) -> head < (x) -> tail \
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? (x) -> tail - (x) -> head \
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: sizeof ((x) -> buf) - ((x) -> head - (x) -> tail)) - 1)
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isc_result_t omapi_connection_require (omapi_object_t *, unsigned);
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isc_result_t omapi_connection_copyout (unsigned char *,
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omapi_object_t *, unsigned);
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isc_result_t omapi_connection_copyin (omapi_object_t *,
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const unsigned char *, unsigned);
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isc_result_t omapi_connection_flush (omapi_object_t *);
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isc_result_t omapi_connection_get_uint32 (omapi_object_t *, u_int32_t *);
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isc_result_t omapi_connection_put_uint32 (omapi_object_t *, u_int32_t);
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isc_result_t omapi_connection_get_uint16 (omapi_object_t *, u_int16_t *);
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isc_result_t omapi_connection_put_uint16 (omapi_object_t *, u_int32_t);
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