A Y86 virtual machine/Sequential Simulator by Dom Mills & Trevor Sargent, under the instruction of Michael Harmon as part of CS277, Architecture and Assembly course at Lewis & Clark College.
$ make
$ ./yes example\ binaries/call.yo
or supply a path to any other object file that follows the reduced instruction set described herein.
$ make clean
- %eax: 0
- %ecx: 1
- %edx: 2
- %ebx: 3
- %esp: 4
- %ebp: 5
- %esi: 6
- %edi: 7
- ZF
- SF
- OF
- PC
- STAT
- AOK
- HALT
- INVAD (invalid address)
- INVIN (invalid instruction)
For this assignment, the addressable space is requred to be from 0 - 2 32 -1
Y86 uses a variable length instruction encoding, they vary from 1-6 bytes
- byte 0: instruction|function endcoding
- byte 1: 1 byte registers
- bytes 2 - 4: 4 bytes of immediate value / offset
NOTE: LITTLE ENDIAN BYTE ORDERING
| Instruction | Byte 0 | 1 | 2 | 3 | 4 | 5 | notes |
|---|---|---|---|---|---|---|---|
halt |
0x00 | ||||||
nop |
0x10 | ||||||
rrmovl rA,rB |
0x20 | rArB | (%eax to %ecx would be 0x01) | ||||
irmovl v, rB |
ox30 | FrB | 1F | 01 | 00 | 00 | (register A is immediate (F) and bytes are listed from most to lease significant) |
rmmovl RA, D(vB) |
0x40 | rArB | 00 | 00 | 00 | 00 | offset value D is in the value bytes |
mrmovl D(rA), rB |
0x50 | rArB | 00 | 00 | 00 | 00 | ditto |
jmp |
0x70 | 00 | 00 | 00 | 00 | location goes in value | |
jxx |
0x7x | 00 | 00 | 00 | 00 | location goes in value, variation in j[xx] dictates respective variation in 7[x] | |
OP rA, rB |
0x6X | rArB | |||||
cmovXX: rA, rB |
0x2X | rArB | |||||
call NAME |
0x80 | ||||||
ret |
0x90 | ||||||
push rA |
0xA0 | rArF | |||||
pop rA |
0xB0 | rArF |
0x6x
- addl: 0
- subl: 1 (cmp)
- andl: 2 (test)
- xorl: 3
Condition flags are set identically to IA-32
j[below] or cmov[below]
- le: 1 (<=)
- l: 2 (<)
- e: 3 (==)
- ne: 4 (!=)
- ge: 5 (>=)
- g: 6 (>)
Instructions for the conditional moves follow the same conventions.