Data Movement

There are three instructions that move data between registers inside the processor:

Instruction Operation

Instruction	Operation
mov.s fd, fs	copy 32 bits from float register `$fs`to float register `$fd`
mtc1 rs, fd	move to coprocessor 1 Copy 32 bits from general register `$rs` to float register `$fd`. No data conversion is done. Note: the source register is `$rs` and the destination register is `$fd`, the reverse of the usual order.
mfc1 rd, fs	move from coprocessor 1 copy 32 bits from float register `$fs`to general register `$rd`. No data conversion is done.

mov.s fd, fs

copy 32 bits from float register $fsto float register $fd

mtc1 rs, fd

move to coprocessor 1

Copy 32 bits from general register $rs to float register $fd. No data conversion is done.
Note: the source register is $rs and the destination register is $fd, the reverse of the usual order.

mfc1 rd, fs

move from coprocessor 1

copy 32 bits from float register $fsto general register $rd. No data conversion is done.

These instructions merely copy bit patterns between registers. The pattern is not altered. With the mfc1 instruction, the contents of a floating point register is copied "as is" to a general purpose register. So a complicated calculation with integers can use float registers for intermediate results. And a complicated calculation with floats can use general purpose resisters the same way.

QUESTION 14:

(Thought Question: ) The neg.s fd,fs instruction places the negation of the number in $fsinto $fd. How does it do this?

Answer:

Data Movement

QUESTION 14: