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89 lines
3.5 KiB
Plaintext
89 lines
3.5 KiB
Plaintext
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "nsISupports.idl"
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/**
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* An interface for access to a buffering stream implementation's underlying
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* memory buffer.
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*
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* Stream implementations that QueryInterface to nsIStreamBufferAccess must
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* ensure that all buffers are aligned on the most restrictive type size for
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* the current architecture (e.g., sizeof(double) for RISCy CPUs). malloc(3)
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* satisfies this requirement.
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*/
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[scriptable, uuid(ac923b72-ac87-4892-ac7a-ca385d429435)]
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interface nsIStreamBufferAccess : nsISupports
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{
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/**
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* Get access to a contiguous, aligned run of bytes in the stream's buffer.
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* Exactly one successful getBuffer call must occur before a putBuffer call
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* taking the non-null pointer returned by the successful getBuffer.
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*
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* The run of bytes are the next bytes (modulo alignment padding) to read
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* for an input stream, and the next bytes (modulo alignment padding) to
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* store before (eventually) writing buffered data to an output stream.
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* There can be space beyond this run of bytes in the buffer for further
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* accesses before the fill or flush point is reached.
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*
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* @param aLength
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* Count of contiguous bytes requested at the address A that satisfies
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* (A & aAlignMask) == 0 in the buffer, starting from the current stream
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* position, mapped to a buffer address B. The stream implementation
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* must pad from B to A by skipping bytes (if input stream) or storing
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* zero bytes (if output stream).
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*
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* @param aAlignMask
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* Bit-mask computed by subtracting 1 from the power-of-two alignment
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* modulus (e.g., 3 or sizeof(uint32_t)-1 for uint32_t alignment).
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*
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* @return
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* The aligned pointer to aLength bytes in the buffer, or null if the
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* buffer has no room for aLength bytes starting at the next address A
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* after the current position that satisfies (A & aAlignMask) == 0.
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*/
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[notxpcom,noscript] charPtr getBuffer(in uint32_t aLength, in uint32_t aAlignMask);
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/**
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* Relinquish access to the stream's buffer, filling if at end of an input
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* buffer, flushing if completing an output buffer. After a getBuffer call
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* that returns non-null, putBuffer must be called.
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*
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* @param aBuffer
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* A non-null pointer returned by getBuffer on the same stream buffer
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* access object.
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*
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* @param aLength
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* The same count of contiguous bytes passed to the getBuffer call that
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* returned aBuffer.
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*/
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[notxpcom,noscript] void putBuffer(in charPtr aBuffer, in uint32_t aLength);
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/**
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* Disable and enable buffering on the stream implementing this interface.
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* DisableBuffering flushes an output stream's buffer, and invalidates an
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* input stream's buffer.
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*/
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void disableBuffering();
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void enableBuffering();
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/**
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* The underlying, unbuffered input or output stream.
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*/
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readonly attribute nsISupports unbufferedStream;
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};
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%{C++
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/**
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* These macros get and put a buffer given either an sba parameter that may
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* point to an object implementing nsIStreamBufferAccess, nsIObjectInputStream,
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* or nsIObjectOutputStream.
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*/
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#define NS_GET_BUFFER(sba,n,a) ((sba)->GetBuffer(n, a))
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#define NS_PUT_BUFFER(sba,p,n) ((sba)->PutBuffer(p, n))
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%}
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