Question

Write the MIPS assembly code that creates the 32-bit constant 0010 0000 0000 0001 0100 1001 0010 0100 and stores that value to register $t1. From previous answers, I see that there is an lui and ori code. Where do those come from? Do they come from the mips reference sheet? Can I get a good explanation please.?

Answer 1

Ans. lui $t1, 0x2001 # $t1 = 0010 0000 0000 0001 0000 0000 0000 0000

ori $t1, 0x4924 # $t1 = 0010 0000 0000 0001 0100 1001 0010 0100

->Larger constants can be loaded into a register 16 bits at a time.
->The load upper immediate instruction lui loads the highest 16 bits of a register with a constant, and clears the lowest 16 bits to 0s.
- >Animmediate logical OR, ori, then sets the lower 16 bits.
To load the 32-bit value 0000 0000 0011 1101 0000 1001 0000 0000.

->This illustrates the principle of making the common case fast.
-> Most of the time, 16-bit constants are enough.
-> It’s still possible to load 32-bit constants, but at the cost of two
instructions and one temporary register.
-> Pseudo-instructions may contain large constants. Assemblers including SPIM will translate such instructions correctly.

->The limited 16-bit constant can present problems for accesses to global data.