Document revision date: 30 March 2001

## OpenVMS RTL Library (LIB$) Manual

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## LIB$WAIT

> The Wait a Specified Period of Time routine places the current process into hibernation for the number of seconds specified in its argument.

### Format

> LIB$WAIT seconds [,flags] [,float-type]

### RETURNS

> OpenVMS usage: | cond_value
> type: | longword (unsigned)
> access: | write only
> mechanism: | by value

### Arguments

> #### seconds

> OpenVMS usage: | floating_point
> type: | F_floating
> access: | read only
> mechanism: | by reference

> The number of seconds to wait. The seconds argument contains the address of an F-floating number that is this number.

> The value is rounded to the nearest hundredth-second before use. Seconds must be between 0.0 and 100,000.0.

> #### flags

> OpenVMS usage: | mask_longword
> type: | longword (unsigned)
> access: | read only
> mechanism: | by reference

> Control flags. The flags argument is the address of a longword integer that contains the control flags. The following flag is defined:

> Bit | Value | Description
> --- | --- | ---
> 0 | LIB$K_NOWAKE | LIB$WAIT will not wake in the case of an interrupt.

> This is an optional argument. If omitted, the default is 0, and LIB$WAIT will wake in the case of an interrupt.

> #### float-type

> OpenVMS usage: | longword-unsigned
> type: | longword (unsigned)
> access: | read only
> mechanism: | by reference

> Float type. The float-type argument is the address of a longword integer that determines the floating-point type of the seconds argument. Use one of the following symbols:

> Symbol | Value | Floating-Point Type
> --- | --- | ---
> LIB$K_VAX_F | 0 | F_floating
> LIB$K_VAX_D | 1 | D_floating
> LIB$K_VAX_G | 2 | G_floating
> LIB$K_VAX_H | 3 | H_floating
> LIB$K_IEEE_S | 4 | IEEE_S_floating
> LIB$K_IEEE_T | 5 | IEEE_T_floating

> This is an optional argument. If omitted, the default is F_floating. F_floating is the required float-type when LIB$WAIT is called from a module written in a language that prototypes functions.

### Description

> LIB$WAIT rounds the value specified by seconds to the nearest hundredth-second, uses the $SCHDWK system service to schedule a wakeup for that interval, and then issues the $HIBER system service to hibernate until the wakeup occurs.

> Because of other system activity, the length of time that the process actually waits may be somewhat longer than what was specified by seconds.

> The process hibernates in the caller's access mode; therefore, asynchronous system traps (ASTs) may be delivered while the process is hibernating. However, if the process hibernates at AST level, further ASTs can not be delivered.

> When the LIB$K_NOWAIT control flag is used, LIB$WAIT makes use of the $SETIMR system service to schedule the wakeup, and then issues a $SYNCH system service call to check for the completion status. In this case, LIB$WAIT will not be interrupted by $WAKE. Use LIB$K_NOWAKE when it is necessary for the wait to be completed without interruption.

> Note The NOWAKE option makes use of the $SETIMR and $SYNCH system services. Because use of these services requires that an AST be delivered, you should not use LIB$WAIT with the LIB$K_NOWAKE control flag at AST level.

> See the OpenVMS System Services Reference Manual for more information.

### Condition Values Returned

> SS$_NORMAL | Routine successfully completed.
> LIB$_INVARG | Invalid argument. The value of seconds was less than 0 or greater than 100,000.0
> LIB$_WRONUMARG | Wrong number of arguments. An incorrect number of arguments was passed to LIB$WAIT.

Any condition values returned by the $SCHDWK or SETIMR system services, or by the RTL routine LIB$CVT_FTOF.

### Example

    IDENTIFICATION DIVISION.
    PROGRAM-ID. T3.
    DATA DIVISION.
    WORKING-STORAGE SECTION.
    01    WAIT-TIME    COMP-1.
    01    FLOAT-TYPE   PIC 9(5) COMP VALUE 0.
    PROCEDURE DIVISION.
    p0.    MOVE 10 TO WAIT-TIME.
           CALL "LIB$WAIT"
           USING BY REFERENCE WAIT_TIME, OMITTED,
                 BY REFERENCE FLOAT-TYPE.
           STOP RUN.

> This COBOL program demonstrates the use of LIB$WAIT on both OpenVMS VAX and OpenVMS Alpha systems. When run, the process performs a 10 second wait.

## Part 3
CVT$ Reference Section

This part provides a detailed discussion of the routines provided by the OpenVMS RTL (CVT$) facility.

## CVT$CONVERT_FLOAT

> The Convert Floating-Point Data Type routine provides a simplified options-interface for converting a floating-point data type to another supported floating-point data type.

### Format

> CVT$CONVERT_FLOAT input_value, input_type_code, output_value, output_type_code, options

### RETURNS

> OpenVMS usage: | cond_value
> type: | longword (unsigned)
> access: | write only
> mechanism: | by value

### Arguments

> #### input_value

> OpenVMS usage: | varying_arg
> type: | unspecified
> access: | read only
> mechanism: | by reference

> The address of a data area containing a floating-point number that is to be converted. The input_value argument may contain floating-point data in F_Floating, D_Floating, G_Floating, H_Floating, IEEE_S_Floating, IEEE_T_Floating, IEEE_X_Floating, IBM_Long_Floating, IBM_Short_Floating, or CRAY_Floating format. The value of the input_type_code argument determines the format and size of the input_value argument.

> #### input_type_code

> OpenVMS usage: | longword_unsigned
> type: | longword (unsigned)
> access: | read only
> mechanism: | by value

> The value of a longword bit mask specifying the type of floating-point data being passed in the input_value argument. Valid type codes are:

> input_type_code | Format | Size in Bytes
> --- | --- | ---
> CVT$K_VAX_F | F_Floating | 4
> CVT$K_VAX_D | D_Floating | 8
> CVT$K_VAX_G | G_Floating | 8
> CVT$K_VAX_H | H_Floating | 16
> CVT$K_IEEE_S | IEEE_S_Floating | 4
> CVT$K_IEEE_T | IEEE_T_Floating | 8
> CVT$K_IEEE_X | IEEE_X_Floating | 16
> CVT$K_IBM_LONG | IBM_Long_Floating | 8
> CVT$K_IBM_SHORT | IBM_Short_Floating | 4
> CVT$K_CRAY | CRAY_Floating | 8

> Declarations for the input_type_code argument are in the $CVTDEF module found in the system symbol libraries.

> #### output_value

> OpenVMS usage: | varying_arg
> type: | unspecified
> access: | write only
> mechanism: | by reference

> The address of a data area that receives the converted floating-point number. The output_value argument can contain floating-point data in F_Floating, D_Floating, G_Floating, H_Floating, IEEE_S_Floating, IEEE_T_Floating, IEEE_X_Floating, IBM_Long_Floating, IBM_Short_Floating, or CRAY_Floating format. The value of the output_type_code argument determines the size and format of the data placed into the output_value argument.

> #### output_type_code

> OpenVMS usage: | longword_unsigned
> type: | longword (unsigned)
> access: | read only
> mechanism: | by value

> The value of a longword bit mask specifying the type of floating-point data that the input_value argument will be converted into and returned in the output_value argument. Valid type codes are:

> output_type_code | Format | Size in Bytes
> --- | --- | ---
> CVT$K_VAX_F | F_Floating | 4
> CVT$K_VAX_D | D_Floating | 8
> CVT$K_VAX_G | G_Floating | 8
> CVT$K_VAX_H | H_Floating | 16
> CVT$K_IEEE_S | IEEE_S_Floating | 4
> CVT$K_IEEE_T | IEEE_T_Floating | 8
> CVT$K_IEEE_X | IEEE_X_Floating | 16
> CVT$K_IBM_LONG | IBM_Long_Floating | 8
> CVT$K_IBM_SHORT | IBM_Short_Floating | 4
> CVT$K_CRAY | CRAY_Floating | 8

> Declarations for the output_type_code argument are in the $CVTDEF module found in the system symbol libraries.

> #### options

> OpenVMS usage: | mask_longword
> type: | longword (unsigned)
> access: | read only
> mechanism: | by value

> Conversion option specifier. The options argument is the address of a longword bit mask in which each option bit set causes the corresponding option to be used during the conversion.

> The following options can be specified using the options argument:

> Option | Description
> --- | ---
> CVT$M_ROUND_TO_NEAREST | The default rounding option for conversions to IEEE data types. This IEEE Std. 754 rounding mode results in the representable output value nearest to the infinitely precise result. If the two nearest representable values are equally near, the one whose least significant bit is 0 is the result.
> CVT$M_VAX_ROUNDING | The default rounding option for conversions to non-IEEE data types. Performs "traditional" style rounding. This mode results in the representable output value nearest to the infinitely precise result. If the two nearest representable values are equally near, the output value is the closest to either positive infinity or negative infinity, depending on the sign of the input value.
> CVT$M_TRUNCATE | Round the output value toward zero (truncate).
> CVT$M_ROUND_TO_POS | Round the output value toward positive infinity.
> CVT$M_ROUND_TO_NEG | Round the output value toward negative infinity.
> CVT$M_BIG_ENDIAN | Interprets IEEE data types as Big Endian.
> CVT$M_ERR_UNDERFLOW | Report underflow conditions as errors.

> Declarations for the options argument are in the $CVTDEF module found in the system symbol libraries.

### Description

> CVT$CONVERT_FLOAT is a general-purpose, floating-point conversion routine that converts any input_type_code floating-point data type into any output_type_code floating-point data type. The conversion is subject to the options specified in the options argument.

> Note OpenVMS compilers do not support arithmetic operations for all of the above floating-point data types. Additional floating-point data types are supported by this routine for data conversion purposes only.

### Condition Values Returned

> CVT$_NORMAL | Normal successful completion.
> CVT$_INPCONERR | Input conversion error.
> CVT$_INVINPTYP | Invalid input type code.
> CVT$_INVOPT | Invalid option argument.
> CVT$_INVOUTTYP | Invalid output type code.
> CVT$_INVVAL | Input value was an invalid number or NaN.
> CVT$_NEGINF | Input value was negative infinity.
> CVT$_OUTCONERR | Output conversion error.
> CVT$_OVERFLOW | Overflow detected during conversion.
> CVT$_POSINF | Input value was positive infinity.
> CVT$_UNDERFLOW | Underflow detected during conversion.

Return status values are in the $CVTMSG module found in the system symbol libraries.

### Example

    /*
    ** ===================================================================
    **
    **  Example of CVT$CONVERT_FLOAT
    **
    ** -------------------------------------------------------------------
    **
    **  This example program reads IEEE T floating-point numbers from an
    **  input file, converts them to VAX D floating-point numbers and
    **  writes the result to an output file.
    **
    **  The input and output file names can be specified as the first and
    **  second arguments on the command line as follows:
    **
    **     $ EXAMPLE IEEE_T_INPUT_FILE.DAT VAX_D_OUTPUT_FILE.DAT
    **
    **  If the input or output files are not included on the command
    **  line then the program prompts the user for them.
    **
    ** ===================================================================
    */
    #include <stdio.h>

    unsigned long CVT$CONVERT_FLOAT(void    *input_value,
                                    unsigned long input_type,
                                    void    *output_value,
                                    unsigned long output_type,
                                    unsigned long options);

    globalvalue CVT$K_VAX_D;
    globalvalue CVT$K_IEEE_T;
    globalvalue CVT$M_ROUND_TO_NEAREST;
    globalvalue CVT$_NORMAL;

    main(int argc, char *argv[])

    {

      double        D_Float_number;
      unsigned long IEEE_Double_number[2];
      unsigned long options;
      char          in_filename[80];
      char          out_filename[80];
      FILE          *in_file, *out_file;
      unsigned long ret_status;

    /*
    ** Find out where we are going to get the data from.
    ** First look at the first argument of the command line.
    ** If nothing is there, then attempt to use IEEE_T_IN.DAT.
    ** =================================================================
    */
    if (argc == 1)
    {
      printf("Enter input data file: [IEEE_T_IN.DAT]: ");
      if (gets(in_filename) == NULL)
        exit(1);

      if (strlen(in_filename) == 0)
        strcpy(in_filename, "IEEE_T_IN.DAT");
    }
    else
      strcpy(in_filename, argv[1]);

    /*
    ** Find out where we are going to put the output data.
    ** First look at the second argument of the command line.
    ** If nothing is there, then put it in VAX_D_OUT.DAT
    ** =================================================================
    */
    if (argc <= 2)
    {
      printf("Enter output data file: [VAX_D_OUT.DAT]: ");
      if (gets(out_filename) == NULL)
        exit(1);

      if (strlen(out_filename) == 0)
        strcpy(out_filename, "VAX_D_OUT.DAT");
    }
    else
      strcpy(out_filename, argv[2]);

    /*
    ** Open the input and output files.
    ** -----------------------------------------------------------------
    */
    if ((in_file = fopen(in_filename, "r")) == NULL)
    {
      fprintf(stderr, "%s couldn't open file %s\n", argv[0], in_filename);
      exit(1);
    }

    out_file = fopen(out_filename, "wb");

    options     = CVT$M_ROUND_TO_NEAREST;
    ret_status  = CVT$_NORMAL;

    /*
    ** Read in each number from the file, convert it, and write it to
    ** the output file.
    ** =================================================================
    */
    while ((fread (&IEEE_Double_number[0],
                   sizeof(IEEE_Double_number),
                   1,
                   in_file) == 1) &&
           (ret_status == CVT$_NORMAL))
    {
      ret_status = CVT$CONVERT_FLOAT(&IEEE_Double_number[0], CVT$K_IEEE_T,
                                     &D_Float_number, CVT$K_VAX_D,
                                     options);

      if (ret_status == CVT$NORMAL)
      {
        fwrite(&D_Float_number, sizeof(D_Float_number), 1, out_file);
        printf("Converted data: %lf.\n", D_Float_number);
      }
    }
    fclose(in_file);
    fclose(out_file);

    if (ret_status == CVT$_NORMAL)
      exit(1);
    else
      exit(ret_status);
    }

## CVT$FTOF

> The Convert Floating-Point Data Type routine converts floating-point data types to other supported floating-point data types and allows additional control over the converted results. CVT$FTOF functionality is also available on other platforms supported by Compaq.

### Format

> status = CVT$FTOF input_value, input_type_code, output_value, output_type_code, options

### RETURNS

> OpenVMS usage: | mask_longword
> type: | longword (unsigned)
> access: | write only
> mechanism: | by value

> The status return value is an unsigned longword bit mask containing the condition codes raised by the function. CVT$FTOF returns CVT$K_NORMAL; otherwise, it sets one or more recoverable and unrecoverable conditions. Use the following condition names to determine which conditions are set:

> Condition Name | Condition (always reported by default)
> --- | ---
> CVT$K_NORMAL | Normal successful completion.
> CVT$M_INVALID_INPUT_TYPE | Invalid input type code.
> CVT$M_INVALID_OUTPUT_TYPE | Invalid output type code.
> CVT$M_INVALID_OPTION | Invalid option argument.

> Condition Name | Condition (reported only if the CVT$M_REPORT_ALL option is selected)
> --- | ---
> CVT$M_RESULT_INFINITE | Conversion produced an infinite result. 1
> CVT$M_RESULT_DENORMALIZED | Conversion produced a denormalized result. 1
> CVT$M_RESULT_OVERFLOW_RANGE | Conversion yielded an exponent greater than 60000 (8). 2
> CVT$M_RESULT_UNDERFLOW_RANGE | Conversion yielded an exponent less than 20000 (8). 2
> CVT$M_RESULT_UNNORMALIZED | Conversion produced an unnormalized result. 3
> CVT$M_RESULT_INVALID | Conversion result is either ROP (reserved operand), NaN (not a number), or closest equivalent. CRAY and IBM data types return 0. 4
> CVT$M_RESULT_OVERFLOW | Conversion resulted in overflow. 4
> CVT$M_RESULT_UNDERFLOW | Conversion resulted in underflow. 4
> CVT$M_RESULT_INEXACT | Conversion resulted in a loss of precision. 4

1For IEEE data type conversions.
2For CRAY data type conversions.
3For IBM data type conversions.
4For all data type conversions.

Return status values are in the $CVTDEF module in the system symbol libraries.

### Arguments

> #### input_value

> OpenVMS usage: | varying_arg
> type: | unspecified
> access: | read only
> mechanism: | by reference

> The address of a data area containing a floating-point number to be converted. The number can be floating-point data in one of the following formats:

> F_Floating | Big_Endian_IEEE_S_Floating
> D_Floating | Big_Endian_IEEE_T_Floating
> G_Floating | Big_Endian_IEEE_X_Floating
> H_Floating | IBM_Long_Floating
> IEEE_S_Floating | IBM_Short_Floating
> IEEE_T_Floating | CRAY_Floating_Single
> IEEE_X_Floating |

> The value of the input_type_code argument determines the format and size of the input_value argument.

> #### input_type_code

> OpenVMS usage: | longword_unsigned
> type: | longword (unsigned)
> access: | read only
> mechanism: | by value

> The value of a longword bit mask specifying the type of floating-point data being passed in the input_value argument. Valid type codes are:

> Input_type_code | Format | Size in Bytes
> --- | --- | ---
> CVT$K_VAX_F | F_Floating | 4
> CVT$K_VAX_D | D_Floating | 8
> CVT$K_VAX_G | G_Floating | 8
> CVT$K_VAX_H | H_Floating | 16
> CVT$K_IEEE_S | IEEE_S_Floating | 4
> CVT$K_IEEE_T | IEEE_T_Floating | 8
> CVT$K_IEEE_X | IEEE_X_Floating | 16
> CVT$K_BIG_ENDIAN_IEEE_S | Big_Endian_IEEE_S_Floating | 4
> CVT$K_BIG_ENDIAN_IEEE_T | Big_Endian_IEEE_T_Floating | 8
> CVT$K_BIG_ENDIAN_IEEE_X | Big_Endian_IEEE_X_Floating | 16
> CVT$K_IBM_LONG | IBM_Long_Floating | 8
> CVT$K_IBM_SHORT | IBM_Short_Floating | 4
> CVT$K_CRAY_SINGLE | CRAY_Floating | 8

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