Re: [fpc-pascal] Converting big-endian signed 16bits values to fpc integer
Just use the BEtoN function. That will convert whatever big-endian number to your native endian. I don't know what speed it has, but it sure is elegant :) Den 16-04-2012 00:38, Giuliano Colla skrev: I'm dealing with a large number of data coming from an external device. They are big-endian 16 bits signed numbers, which must be converted to integer and to real to perform calculations. Besides the obvious solutions of treating them as isolated bytes, multipying by 256 the highest, adding the lower, and oring wit $, or whatever sizeof(Integer) suggests if the result is bigger than 32767, is there a more efficient and elegant way to achieve the result? I'm a bit lost on all available data types, and unable to tell apart the ones which are platform specific and the ones which are not, which assignments give the proper result and which do not. Any suggestion would be greatly appreciated. Giuliano Colla ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Converting big-endian signed 16bits values to fpc integer
On 16 Apr 2012, at 00:38, Giuliano Colla wrote: I'm dealing with a large number of data coming from an external device. They are big-endian 16 bits signed numbers, which must be converted to integer and to real to perform calculations. Besides the obvious solutions of treating them as isolated bytes, multipying by 256 the highest, adding the lower, and oring wit $, or whatever sizeof(Integer) suggests if the result is bigger than 32767, is there a more efficient and elegant way to achieve the result? Call BEtoN() on them (Big Endian to Native byte order). Note that this routine is overloaded for all integer sizes 1, and that FPC extends the size of any number 32/64 bits (depending on the architecture) to 32/64 bits when performing almost any operation on it. It's therefore probably the safest to call it as BEtoN(smallint(value)) to ensure that the correct overload is selected. Jonas___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Converting big-endian signed 16bits values to fpc integer
Il 16/04/2012 00:42, Jonas Maebe ha scritto: On 16 Apr 2012, at 00:38, Giuliano Colla wrote: I'm dealing with a large number of data coming from an external device. They are big-endian 16 bits signed numbers, which must be converted to integer and to real to perform calculations. Besides the obvious solutions of treating them as isolated bytes, multipying by 256 the highest, adding the lower, and oring wit $, or whatever sizeof(Integer) suggests if the result is bigger than 32767, is there a more efficient and elegant way to achieve the result? Call BEtoN() on them (Big Endian to Native byte order). Note that this routine is overloaded for all integer sizes 1, and that FPC extends the size of any number 32/64 bits (depending on the architecture) to 32/64 bits when performing almost any operation on it. It's therefore probably the safest to call it as BEtoN(smallint(value)) to ensure that the correct overload is selected. I was sure that hidden somewhere there was a better way! Thanks a lot Giuliano ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Converting big-endian signed 16bits values to fpc integer
On 04/15/12 18:38, Giuliano Colla wrote: I'm dealing with a large number of data coming from an external device. They are big-endian 16 bits signed numbers, which must be converted to integer and to real to perform calculations. Besides the obvious solutions of treating them as isolated bytes, multipying by 256 the highest, adding the lower, and oring wit $, or whatever sizeof(Integer) suggests if the result is bigger than 32767, is there a more efficient and elegant way to achieve the result? I'm a bit lost on all available data types, and unable to tell apart the ones which are platform specific and the ones which are not, which assignments give the proper result and which do not. Any suggestion would be greatly appreciated. Giuliano Colla There exists the BEtoN and LEtoN functions you can use. There exists the BEtoN and LEtoN functions you can use. (NtoLE and NtoBE also) var Data: SmallInt; // 16 bit signed type ... Data := GetBENumberFromWherever; Data := BEtoN(Data); I'm not sure about real types. If they are 32 bits and sent in two pieces then you could just do var Data: Single; // 4 bytes DataArray: array[0..1] of Word absolute Data; ... // I'm not sure how the data is represented in memory for floats. DataArray[1] := BEtoN(Word(GetBENumberFromWherever)); DataArray[0] := BEtoN(Word(GetBENumberFromWherever)); Anyway you get the idea. Probably you will have to experiment to achieve exactly what you want. Someone else probably has a better answer. Regards, Andrew ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
