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Technical Support On-Line Manuals C251 User's Guide ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
bitThe bit type defines a single-bit variable. It is used as follows: bit name <[>= value<]>; Where
The bit type may be used for variable declarations, argument lists, and function-return values. A bit variable is declared like other C data types. For example: static bit done_flag = 0; /* bit variable */ bit testfunc ( /* bit function */ bit flag1, /* bit arguments */ bit flag2) { . . . return (0); /* bit return value */ } All bit variables are stored in a bit segment located in the 8051-compatible internal memory area of the 251. Because this area is only 16 bytes long, a maximum of 128 bit variables may be declared within any one scope. Note
The 251 supports an extended bit-addressable area that is located in the data memory address range 0x20-0x7F. This extended bit area supports a maximum of 768 bit variables. To locate a bit in the extended bit area, specify bit ebdata as shown in the example below. bit ebdata state1; /* bit in 251 extended space */ bit function (bit flag) { /* parameters are only in 8051 space */ bit ebdata local_bit; /* local bit in 251 space */ local_bit = flag; return (local_bit); /* return 251 extended bit */ } Note
The following restrictions apply to bit variables and bit declarations:
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