SH7750_08 Datasheet, PDF (280/1162 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

Section 6 Floating-Point Unit (FPU)
Since approximate-value computations are performed to enable high-speed computation, the
inexact exception (I) bit in the cause field and flag field is always set to 1 when an FIPR
instruction is executed. Therefore, if the corresponding bit is set in the enable field, enable
exception handling will be executed.
FTRV XMTRX, FVn (n: 0, 4, 8, 12): This instruction is basically used for the following
purposes:
• Matrix (4 × 4) ⋅ vector (4):
This operation is generally used for viewpoint changes, angle changes, or movements called
vector transformations (4-dimensional). Since affine transformation processing for angle +
parallel movement basically requires a 4 × 4 matrix, the FPU supports 4-dimensional
operations.
• Matrix (4 × 4) × matrix (4 × 4):
This operation requires the execution of four FTRV instructions.
Since approximate-value computations are performed to enable high-speed computation, the
inexact exception (I) bit in the cause field and flag field is always set to 1 when an FTRV
instruction is executed. Therefore, if the corresponding bit is set in the enable field, enable
exception handling will be executed. For the same reason, it is not possible to check all data types
in the registers beforehand when executing an FTRV instruction. If the V bit is set in the enable
field, enable exception handling will be executed.
FRCHG: This instruction modifies banked registers. For example, when the FTRV instruction is
executed, matrix elements must be set in an array in the background bank. However, to create the
actual elements of a translation matrix, it is easier to use registers in the foreground bank. When
the LDC instruction is used on FPSCR, this instruction expends 4 to 5 cycles in order to maintain
the FPU state. With the FRCHG instruction, an FPSCR.FR bit modification can be performed in
one cycle.
6.6.2 Pair Single-Precision Data Transfer
In addition to the geometric operation instructions, the FPU also supports high-speed data transfer
instructions.
When FPSCR.SZ = 1, the FPU can perform data transfer by means of pair single-precision data
transfer instructions.
• FMOV DRm/XDm, DRn/XDRn (m, n: 0, 2, 4, 6, 8, 10, 12, 14)
• FMOV DRm/XDm, @Rn (m: 0, 2, 4, 6, 8, 10, 12, 14; n: 0 to 15)
Rev.7.00 Oct. 10, 2008 Page 196 of 1074
REJ09B0366-0700