This page does not represent the most current semester of this course; it is present merely as an archive.
This is a small homework to expose you to the hcl2d tool we'll use for the next several labs and homeworks.
Copy tiny.hcl to pc.hcl; you will be editing pc.hcl for this lab
Review the built-in functionality at the end of README.md:
##################### begin builtin signals ########################
const STAT_BUB = 0, STAT_AOK = 1, STAT_HLT = 2; # expected behavior
const STAT_ADR = 3, STAT_INS = 4, STAT_PIP = 5; # error conditions
wire Stat:3; # input (one of the above constants)
const REG_EAX = 0, REG_ECX = 1, REG_EDX = 2, REG_EBX = 3;
const REG_ESP = 4, REG_EBP = 5, REG_ESI = 6, REG_EDI = 7;
const REG_NONE = 0xf;
wire rvalA:32, rvalB:32; # outputs
wire dstM:4, dstE:4, srcA:4, srcB:4; # selector inputs
wire wvalE:32, wvalM:32; # data inputs
wire pc:32; # address of next instruction to fetch
wire i6bytes:48; # output value of instruction fetched
wire addr:32; # input: address of memory read/write op
wire wdval:32; # input: value to write if dwrite is true
wire dwrite:1, dread:1; # input. At most one should be 1
wire rvalM:32; # output: value read if dread was true
###################### end builtin signals #########################Edit pc.hcl so that the pc updates work in the case where there are not jump, call, or return statements. You'll almost certainly want to consult figure 4.2 (page 338) to do this.
Read all of the comments. Really, all of them.
We won't be needing to use the register file in this assignment, so remove the block of hcl that starts with the comment # let's also increment a register… (but keep the line that updates p_pc)
Have the hcl read each instruction and get it's icode (tiny.hcl does this already)
Set the Stat output to STAT_INS if there is a jXX, call, or ret icode; to STAT_HLT if there is a halt icode; and to STAT_AOK for all other icodes.
There is already a line Stat = [ that set the Stat to either STAT_AOK or STAT_HLT. You'll need to change it to also set STAT_INS for some icodes.
Update the p_pc to be pc + an appropriate offset (1, 2, 5, or 6, depending on the icode).
There is a line p_pc = pc + 1; – you will need to change it so that uses a mux to select what number is added to pc. Note: you cannot use a mux as an operand to a mathematical operator like +.
Example runs (all assume you run your simulator with the -q flag) I have removed the "Time used" line because it does not matter for this assignment.
y86/prog1.yo should give
+------------------- halted in state: --------------------------+
| EAX: 0 ECX: 0 EDX: 0 EBX: 0 |
| ESP: 0 EBP: 0 ESI: 0 EDI: 0 |
| register P(N) { pc=00000012 } |
| used memory: _0 _1 _2 _3 _4 _5 _6 _7 _8 _9 _a _b _c _d _e _f |
| 0x0000000_: 30 f2 0a 00 00 00 30 f0 03 00 00 00 10 10 10 60 |
| 0x0000001_: 20 00 |
+---------------------------------------------------------------+
Cycles run: 7y86/prog7.yo should give
+--------------- error caused in state: ------------------------+
| EAX: 0 ECX: 0 EDX: 0 EBX: 0 |
| ESP: 0 EBP: 0 ESI: 0 EDI: 0 |
| register P(N) { pc=0000000b } |
| used memory: _0 _1 _2 _3 _4 _5 _6 _7 _8 _9 _a _b _c _d _e _f |
| 0x0000000_: 30 f4 30 00 00 00 80 20 00 00 00 30 f2 0a 00 00 |
| 0x0000001_: 00 00 |
| 0x0000002_: 90 20 23 |
+---------------------------------------------------------------+
Cycles run: 2
Error code: 4 (Invalid Instruction)y86/poptest.yo should give
+------------------- halted in state: --------------------------+
| EAX: 0 ECX: 0 EDX: 0 EBX: 0 |
| ESP: 0 EBP: 0 ESI: 0 EDI: 0 |
| register P(N) { pc=00000011 } |
| used memory: _0 _1 _2 _3 _4 _5 _6 _7 _8 _9 _a _b _c _d _e _f |
| 0x0000000_: 30 f4 00 01 00 00 30 f0 cd ab 00 00 a0 0f b0 4f |
| 0x0000001_: 00 |
+---------------------------------------------------------------+
Cycles run: 5Submit a file named pc.hcl on the submission page.