COMPSCI 61C Lecture Notes - Lecture 11: C Data Types, Opcode, Assembly Language

• School: Berkeley
• Department: Computer Science
• Course: COMPSCI 61C
• Professor: Gerald Friedland

Document Summary

De ne elds of he following number of bits each: 6 + 5 + 5 + 16 = 32 bits. Each eld has a name: opcode, rs, rt, immediate. Key concept: only one eld (no rd, so rt is the register to write) is inconsistent with. Especially important that opcode is in the same location. The immediate field: addi, addiu, slti, sltiu, lw, sw the immediate is sign-extended to. 32 bits, so it"s treated as a signed integer. 16 bits can be used to represent immediate up to 216 di erent values. Large enough to handle o set in a typical lw or sw, plus a vast majority of values that will be used in the slti instruction. Mips instruction: addi , , -50 opcode = 8 (look up in table in book) rs = 22 (register containing operand) rt = 21 (target register) immediate = -50 (by default, this is decimal in assembly code.