HD6417750RF240DV Datasheet, PDF (247/1132 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH™ RISC engine Family / SH7750 Series

SH7750, SH7750S, SH7750R Group
Section 6 Floating-Point Unit (FPU)
⎯ Overflow (O):
When rounding mode = RZ, the maximum normalized number, with the same sign as the
unrounded value, is generated.
When rounding mode = RN, infinity with the same sign as the unrounded value is
generated.
⎯ Underflow (U):
When FPSCR.DN = 0, a denormalized number with the same sign as the unrounded value,
or zero with the same sign as the unrounded value, is generated.
When FPSCR.DN = 1, zero with the same sign as the unrounded value, is generated.
⎯ Inexact exception (I): An inexact result is generated.
6.6 Graphics Support Functions
The FPU supports two kinds of graphics functions: new instructions for geometric operations, and
pair single-precision transfer instructions that enable high-speed data transfer.
6.6.1 Geometric Operation Instructions
Geometric operation instructions perform approximate-value computations. To enable high-speed
computation with a minimum of hardware, the FPU ignores comparatively small values in the
partial computation results of four multiplications. Consequently, the error shown below is
produced in the result of the computation:
Maximum error = MAX (individual multiplication result ×
2 ) + MAX (result value × 2 , 2 ) ^{–MIN (number of multiplier significant digits–1, number of multiplicand significant digits–1)}
–23 –149
The number of significant digits is 24 for a normalized number and 23 for a denormalized number
(number of leading zeros in the fractional part).
In future version of SuperH RISC engine family, the above error is guaranteed, but the same result
as SH7750 is not guaranteed.
FIPR FVm, FVn (m, n: 0, 4, 8, 12): This instruction is basically used for the following purposes:
• Inner product (m ≠ n):
This operation is generally used for surface/rear surface determination for polygon surfaces.
• Sum of square of elements (m = n):
This operation is generally used to find the length of a vector.
R01UH0456EJ0702 Rev. 7.02
Sep 24, 2013
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