.. _stdlib_stdbloblib: ================== The Blob library ================== The blob library implements binary data manipulations routines. The library is based on `blob objects` that represent a buffer of arbitrary binary data. --------------- Squirrel API --------------- +++++++++++++++ Global symbols +++++++++++++++ .. js:function:: castf2i(f) casts a float to a int .. js:function:: casti2f(n) casts a int to a float .. js:function:: swap2(n) swap the byte order of a number (like it would be a 16bits integer) .. js:function:: swap4(n) swap the byte order of an integer .. js:function:: swapfloat(n) swaps the byteorder of a float ++++++++++++++++++ The blob class ++++++++++++++++++ The blob object is a buffer of arbitrary binary data. The object behaves like a file stream, it has a read/write pointer and it automatically grows if data is written out of his boundary. A blob can also be accessed byte by byte through the `[]` operator. .. js:class:: blob(size) :param int size: initial size of the blob returns a new instance of a blob class of the specified size in bytes .. js:function:: blob.eos() returns a non null value if the read/write pointer is at the end of the stream. .. js:function:: blob.flush() flushes the stream.return a value != null if succeded, otherwise returns null .. js:function:: blob.len() returns the length of the stream .. js:function:: blob.readblob(size) :param int size: number of bytes to read read n bytes from the stream and returns them as blob .. js:function:: blob.readn(type) :param int type: type of the number to read reads a number from the stream according to the type parameter. `type` can have the following values: +--------------+--------------------------------------------------------------------------------+----------------------+ | parameter | return description | return type | +==============+================================================================================+======================+ | 'l' | processor dependent, 32bits on 32bits processors, 64bits on 64bits processors | integer | +--------------+--------------------------------------------------------------------------------+----------------------+ | 'i' | 32bits number | integer | +--------------+--------------------------------------------------------------------------------+----------------------+ | 's' | 16bits signed integer | integer | +--------------+--------------------------------------------------------------------------------+----------------------+ | 'w' | 16bits unsigned integer | integer | +--------------+--------------------------------------------------------------------------------+----------------------+ | 'c' | 8bits signed integer | integer | +--------------+--------------------------------------------------------------------------------+----------------------+ | 'b' | 8bits unsigned integer | integer | +--------------+--------------------------------------------------------------------------------+----------------------+ | 'f' | 32bits float | float | +--------------+--------------------------------------------------------------------------------+----------------------+ | 'd' | 64bits float | float | +--------------+--------------------------------------------------------------------------------+----------------------+ .. js:function:: blob.resize(size) :param int size: the new size of the blob in bytes resizes the blob to the specified `size` .. js:function:: blob.seek(offset [,origin]) :param int offset: indicates the number of bytes from `origin`. :param int origin: origin of the seek +--------------+-------------------------------------------+ | 'b' | beginning of the stream | +--------------+-------------------------------------------+ | 'c' | current location | +--------------+-------------------------------------------+ | 'e' | end of the stream | +--------------+-------------------------------------------+ Moves the read/write pointer to a specified location. .. note:: If origin is omitted the parameter is defaulted as 'b'(beginning of the stream). .. js:function:: blob.swap2() swaps the byte order of the blob content as it would be an array of `16bits integers` .. js:function:: blob.swap4() swaps the byte order of the blob content as it would be an array of `32bits integers` .. js:function:: blob.tell() returns the read/write pointer absolute position .. js:function:: blob.writeblob(src) :param blob src: the source blob containing the data to be written writes a blob in the stream .. js:function:: blob.writen(n, type) :param number n: the value to be written :param int type: type of the number to write writes a number in the stream formatted according to the `type` parameter `type` can have the following values: +--------------+--------------------------------------------------------------------------------+ | parameter | return description | +==============+================================================================================+ | 'i' | 32bits number | +--------------+--------------------------------------------------------------------------------+ | 's' | 16bits signed integer | +--------------+--------------------------------------------------------------------------------+ | 'w' | 16bits unsigned integer | +--------------+--------------------------------------------------------------------------------+ | 'c' | 8bits signed integer | +--------------+--------------------------------------------------------------------------------+ | 'b' | 8bits unsigned integer | +--------------+--------------------------------------------------------------------------------+ | 'f' | 32bits float | +--------------+--------------------------------------------------------------------------------+ | 'd' | 64bits float | +--------------+--------------------------------------------------------------------------------+ ------ C API ------ .. _sqstd_register_bloblib: .. c:function:: SQRESULT sqstd_register_bloblib(HSQUIRRELVM v) :param HSQUIRRELVM v: the target VM :returns: an SQRESULT :remarks: The function aspects a table on top of the stack where to register the global library functions. initializes and registers the blob library in the given VM. .. _sqstd_getblob: .. c:function:: SQRESULT sqstd_getblob(HSQUIRRELVM v, SQInteger idx, SQUserPointer* ptr) :param HSQUIRRELVM v: the target VM :param SQInteger idx: and index in the stack :param SQUserPointer* ptr: A pointer to the userpointer that will point to the blob's payload :returns: an SQRESULT retrieve the pointer of a blob's payload from an arbitrary position in the stack. .. _sqstd_getblobsize: .. c:function:: SQInteger sqstd_getblobsize(HSQUIRRELVM v, SQInteger idx) :param HSQUIRRELVM v: the target VM :param SQInteger idx: and index in the stack :returns: the size of the blob at `idx` position retrieves the size of a blob's payload from an arbitrary position in the stack. .. _sqstd_createblob: .. c:function:: SQUserPointer sqstd_createblob(HSQUIRRELVM v, SQInteger size) :param HSQUIRRELVM v: the target VM :param SQInteger size: the size of the blob payload that has to be created :returns: a pointer to the newly created blob payload creates a blob with the given payload size and pushes it in the stack.