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POUsing python ctypes to get buffer of floats from shared library into python string
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copied!<p>I'm trying to use python ctypes to use these two C functions from a shared library:</p> <pre> <code>bool decompress_rgb(unsigned char *data, long dataLen, int scale) float* getRgbBuffer()</code></pre> <p>The first function is working fine. I can tell by putting some debug code in the shared library and checking the input.</p> <p>The problem is getting the data out. The RGB buffer is a pointer to a float (obviously) and this pointer stays constant during the life of the application. Therefore whenever I want to decompress an image, I call <code>decompress_rgb</code> and then need to see what's at the location pointed to by <code>getRgbBuffer</code>. I know that the buffer size is (720 * 288 * sizeof(float)) so I guess this has to come into play somewhere.</p> <p>There's no <code>c_float_p</code> type so I thought I'd try this:</p> <pre><code>getRgbBuffer.restype = c_char_p</code></pre> <p>Then I do:</p> <pre><code>ptr = getRgbBuffer() print "ptr is ", ptr</code></pre> <p>which just outputs:</p> <pre><code>ptr = 3078746120</code></pre> <p>I'm guessing that's the actual address rather than the content, but even if I was successfully dereferencing the pointer and getting the contents, it would only be the first char.</p> <p>How can I get the contents of the entire buffer into a python string? </p> <p><strong>Edit:</strong> Had to change:</p> <pre><code>getRgbBuffer.restype = c_char_p</code></pre> <p>to</p> <pre><code>getRgbBuffer.restype = c_void_p</code></pre> <p>but then BastardSaint's answer worked.</p>

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