Writing a custom conversion routine

A custom character set conversion routine is defined as follows:

CS_RETCODE convfunc(context, srcfmt, srcdata,
               destfmt, destdata, destlen)
 CS_CONTEXT         *context;
 CS_DATAFMT          *srcfmt;
 CS_VOID                 *srcdata;
 CS_DATAFMT         *destfmt;
 CS_VOID                *destdata;
 CS_INT                 *destlen;

where:

context is a pointer to a CS_CONTEXT structure.
srcfmt is a pointer to a CS_DATAFMT structure describing the source data. srcfmt→maxlength describes the actual length, in bytes, of the source data.
srcdata is a pointer to the source data.
destfmt is a pointer to a CS_DATAFMT structure describing the destination data. destfmt→maxlength describes the actual length, in bytes, of the destination data space.
destdata is a pointer to the destination data space.
destlen is a pointer to an integer. If the conversion is successful, the custom routine should set *destlen to the number of bytes placed in *destdata.

cs_config is the only CS-Library, Client-Library, or Server-Library routine that can be called from within a custom conversion routine.

CS-Library raises a CS-Library error if the custom routine returns any value other than CS_SUCCEED. The type of error that CS-Library raises depends on the value that the custom routine returns. The following table lists the legal return values for a custom conversion routine:

**Table 4-2: Return values for a custom conversion routine**
Return value	Indicates
CS_SUCCEED	The conversion is successful.
CS_TRUNCATED	The conversion resulted in truncation.
CS_MEM_ERROR	A memory allocation failure has occurred.
CS_EBADXLT	Some characters could not be converted.
CS_ENOXLT	The requested conversion is not supported.
CS_EDOMAIN	The source value is outside the domain of legal values for the datatype.
CS_EDIVZERO	Division by zero is not allowed.
CS_EOVERFLOW	The conversion resulted in overflow.
CS_EUNDERFLOW	The conversion resulted in underflow.
CS_EPRECISION	The conversion resulted in loss of precision.
CS_ESCALE	An illegal scale value was encountered.
CS_ESYNTAX	The conversion resulted in a value that is not syntactically correct for the destination type.
CS_ESTYLE	The conversion operation was stopped due to a style error.