r8a77850anbg Renesas Electronics Corporation., r8a77850anbg Datasheet - Page 170

• Manufacturer Part Number: r8a77850anbg
• Description: Renesas 32-bit Risc Microcomputer Superh? Risc Engine Family
• Manufacturer: Renesas Electronics Corporation.

6. Floating-Point Unit (FPU)
6.6
This LSI 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 perform approximate-value computations. To enable high-speed
computation with a minimum of hardware, this LSI 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 ×
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 a future version of the SH Series, the above error is guaranteed, but the same result between
different processor cores is not guaranteed.
(1)
This instruction is basically used for the following purposes:
• Inner product (m ≠ n):
• Sum of square of elements (m = n):
Since an inexact exception is not detected by an FIPR instruction, the inexact exception (I) bit in
both the FPU exception cause field and flag field are always set to 1 when an FIPR instruction is
executed. Therefore, if the I bit is set in the FPU exception enable field, FPU exception handling
will be executed.
Rev.1.00 Jan. 10, 2008 Page 140 of 1658
REJ09B0261-0100
This operation is generally used for surface/rear surface determination for polygon surfaces.
This operation is generally used to find the length of a vector.
FIPR FVm, FVn (m, n: 0, 4, 8, 12)
Graphics Support Functions
Geometric Operation Instructions
2
–MIN (number of multiplier significant digits–1, number of multiplicand significant digits–1)
) + MAX (result value × 2
–23
, 2
–149
)