Renesas SH7781 - Manual (Page 160)

6. Floating-Point Unit (FPU)
Rev.1.00 Jan. 10, 2008 Page 130 of 1658
REJ09B0261-0100
See section 10, Instruction Descriptions of the SH-4A Extended Functions Software Manual for
details of floating-point operations when a non-number (NaN) is input.
6.2.3 Denormalized Numbers
For a denormalized number floating-point value, the exponent field is expressed as 0, and the
fraction field as a non-zero value.
When the DN bit in FPSCR of the FPU is 1, a denormalized number (source operand or operation
result) is always positive or negative zero in a floating-point operation that generates a value (an
operation other than transfer instructions between registers, FNEG, or FABS).
When the DN bit in FPSCR is 0, a denormalized number (source operand or operation result) is
processed as it is. See section 10, Instruction Descriptions of the SH-4A Extended Functions
Software Manual for details of floating-point operations when a denormalized number is input.