Y86 Assembly Language Instruction Reference

Instruction Description Examples nop No-Operation (does nothing) nop halt Stops the simulator halt rrmovl rA, rB register-to-register move Copies from register rA to register rB rrmovl %eax, %ecx rrmovl %esp,%ebp irmovl V, rB immediate-to-register move puts 32 bit immediate value in register rB irmovl $1234,%eax rmmovl rA D(rB) register-to-memory move Copies from register rA to memory location Mem[rB+D] rmmovl %eax,-4(%ebp) rmmovl %edx,0x100(%esi) mrmovl D(rB),rA memory-to-register move copies contents of Mem[rB+D] to register rA mrmovl 8(%ebp),%eax mrmovl 0(%ecx),%edx addl rA, rB add: rB = rB + rA also sets condition code bits addl %eax, %edx subl rA, rB subtract: rB = rB - rA also sets condition code bits subl %eax, %edx andl rA, rB bitwise logical and: rB = rA & rB also sets condition code bits andl %eax, %edx xorl rA, rB exclusive or: rB = rA ^ rB also sets condition code bits xorl %eax, %eax jmp Dest unconditional jump to Dest (32 bit address) jmp 0x1000000 jmp foo jle Dest jump if previous result was less than or equal to 0. based on signed arithmetic (to determine <= ) jle foo jl Dest jump if previous result was less than 0. based on signed arithmetic (to determine <) jl foo je Dest jump if previous result was equal to 0. je foo jne Dest jump if previous result was not equal to 0. jne foo jge Dest jump if previous result was greater than or equal to 0. based on signed arithmetic (to determine >= ) jge foo jg Dest jump if previous result was greater than 0. based on signed arithmetic (to determine >) jg foo call Dest Initiates a subroutine call to Dest (32 bit address) pushes return address on stack and jumps to Dest call strcpy ret return from subroutine. pops return address from stack and jumps to return address ret pushl rA push register rA on the stack. Mem[%esp-4] = rA, %esp=%esp-4 pushl %eax popl rA pop from stack to register rA rA = Mem[%esp], %esp = %esp+4 popl %ebp