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52 lines
1.5 KiB
52 lines
1.5 KiB
name: duk_push_external_buffer
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proto: |
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void duk_push_external_buffer(duk_context *ctx);
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stack: |
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[ ... ] -> [ ... buf! ]
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summary: |
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<p>Allocate an external buffer and push it to the value stack. An external
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buffer refers to a user allocated external buffer which is not memory
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managed by Duktape. The initial external buffer pointer is NULL and size
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is zero. You can use
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<code><a href="#duk_config_buffer">duk_config_buffer()</a></code>
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to update the external buffer pointer and size.</p>
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<p>External buffers are useful to allow ECMAScript code access externally
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allocated data structures. You can use it to e.g. write bytes to an
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externally allocated frame buffer. The external buffer has no alignment
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requirements (Duktape makes no alignment assumptions when accessing it).</p>
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example: |
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void *p;
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duk_size_t len;
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/* Allocate a frame buffer from a hypothetical graphics library.
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* The frame buffer is allocated outside of Duktape.
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*/
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p = allocate_frame_buffer(1920 /*width*/, 1080 /*height*/);
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len = 1920 * 1080 * 4;
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/* Create an external buffer pointing to the frame buffer. */
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duk_push_external_buffer(ctx);
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duk_config_buffer(ctx, -1, p, len);
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/* ECMAScript code with access to the buffer object could now do
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* something like:
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*
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* buf[100] = 123;
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*
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* Calling code must make sure ECMAScript never reads/writes an
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* external buffer whose backing buffer is no longer valid.
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*/
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tags:
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- stack
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- buffer
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seealso:
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- duk_config_buffer
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introduced: 1.3.0
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