Convert Decimal Form to Floating-Point (CVTDFFP)

Instruction Syntax

Operand 2: Packed scalar or zoned scalar (1 to 31 digits).

Operand 3: Packed scalar or zoned scalar (1 to 31 digits).

Description:

This instruction converts the decimal form of a floating-point value specified by a decimal exponent and a decimal significand to binary floating-point format, and places the result in the receiver operand. The decimal exponent (operand 2) and decimal significand (operand 3) are considered to specify a decimal form of a floating-point number. The value of this number is considered to be as follows:

Value = S * (10**E)

WHERE:

S =

The value of the decimal significand operand.

E =

The value of the decimal exponent operand.

*

Denotes multiplication.

**

Denotes exponentiation.

The decimal exponent must be specified as a decimal integer value; no fractional digit positions may be specified in its definition. The decimal exponent is a signed integer value specifying a power of 10 which gives the floating-point value its magnitude. A decimal exponent value too large or too small to be represented in the receiver will result in the signaling of the appropriate floating-point overflow (hex 0C06) exception or floating-point underflow (hex 0C07) exception.

The decimal significand must be specified as a decimal value with a single integer digit position and optional fractional digit positions. The decimal significand is a signed decimal value specifying decimal digits which give the floating-point value its precision. The significant digits of the decimal significand are considered to start with the leftmost nonzero decimal digit and continue to the right to the end of the decimal significand value. Significant digits beyond 7 for a short float receiver, and beyond 15 for a long float receiver exceed the precision provided for in the binary floating-point receiver. These excess digits do participate in the conversion to provide for uniqueness of the conversion as well as for proper rounding.

The decimal form floating-point value specified by the decimal exponent and decimal significand operands is converted to a binary floating-point number and rounded to the precision of the result field as follows:

Source values which, in magnitude M, are in the range where (10**31-1) * 10**-31 <= M <= (10**31-1) *10**+31 are converted subject to the normal rounding error defined for the floating-point rounding modes.

Source values which, in magnitude M, are in the range where (10**31-1) * 10**-31 > M > (10**31-1) *10**+31 are converted such that the rounding error incurred on the conversion may exceed that defined above. For round to nearest, this error will not exceed by more than .47 units in the least significant digit position of the result in relation to the error that would be incurred for normal rounding. For the other floating-point rounding modes, this error will not exceed 1.47 units in the least significant digit position of the result.

The converted and rounded value is then assigned to the floating-point receiver.

Authorization Required

• None

Lock Enforcement

• None

Exceptions

• 06 Addressing
  • 0601 Space Addressing Violation
  • 0602 Boundary Alignment
  • 0603 Range
• 08 Argument/Parameter
  • 0801 Parameter Reference Violation
• 0C Computation
  • 0C02 Decimal Data
  • 0C06 Floating-Point Overflow
  • 0C07 Floating-Point Underflow
  • 0C0D Floating-Point Inexact Result
• 10 Damage Encountered
  • 1004 System Object Damage State
  • 1044 Partial System Object Damage
• 1C Machine-Dependent
  • 1C03 Machine Storage Limit Exceeded
• 20 Machine Support
  • 2002 Machine Check
  • 2003 Function Check
• 22 Object Access
  • 2201 Object Not Found
  • 2202 Object Destroyed
  • 2203 Object Suspended
  • 2208 Object Compressed
  • 220B Object Not Available
• 24 Pointer Specification
  • 2401 Pointer Does Not Exist
  • 2402 Pointer Type Invalid
• 2E Resource Control Limit
  • 2E01 User Profile Storage Limit Exceeded
• 32 Scalar Specification
  • 3201 Scalar Type Invalid
• 36 Space Management
  • 3601 Space Extension/Truncation
• 44 Protection Violation
  • 4401 Object Domain or Hardware Storage Protection Violation
  • 4402 Literal Values Cannot Be Changed