The psp's VFPU (Vector Floating Point Unit) is a coprocessor that can perform quite a few useful operations. The main purpose of it is vector and matrix processing, but it also supports trigonemtric functions and other mathematical operations, conversions, and mathematical constants.
The VFPU has 128 single precision floating point registers (IEEE 754), but they are arranged and accessed in various ways that make it very flexible. Many of the instructions for the VFPU support operations on:
And if that weren't enough, it can work with matrices in normal or transposed orders.
The registers are grouped into 8 blocks of 16 registers each. This gives you enough room to work with 8 4x4 matrices, 8 3x3 matrices, 32 2x2 matrices. Or you can store up to 32 quad vectors, 40 triple vectors, 64 paired vectors, or 128 single values.
The register names you use on the VFPU depends highly on the instruction being performed, and can quickly become a nightmare when trying to figure out how to access or modify certain registers. Register names are numbered with 3 digits: Matrix, Column and Row. The tables below show how single, pair, triple, quad and matrix registers are mapped within a single 16 register block
Repeat all of the above with the other 7 blocks of registers. Just change the first digit of the register names to work on a different set
Reading/writing data to the VFPU
There are 6 instructions that are used to read or write values into the VFPU registers