Change instruction encodings to avoid null instructions

Lots of null bytes in a row are a common thing, so the instructions
available can't start with a null pair of bytes anymore.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

src/libvm/examples/deadbeef.asm

@@ -21,7 +21,7 @@
         jnz end
         mov %status, $1
     end:
-        div %r0, $0
+        int $0, $0
         halt
     .export main
 

src/libvm/src/inst.rs

@@ -23,32 +23,32 @@ macro_rules! instructions {
 pub type InstOp = u16;
 
 instructions! {
-    ADD     = 0x0000,
+    ADD     = 0x1000,
-    SUB     = 0x0001,
+    SUB     = 0x1001,
-    MUL     = 0x0002,
+    MUL     = 0x1002,
-    DIV     = 0x0003,
+    DIV     = 0x1003,
-    IDIV    = 0x0004,
+    IDIV    = 0x1004,
-    MOD     = 0x0005,
+    MOD     = 0x1005,
-    AND     = 0x0006,
+    AND     = 0x1006,
-    OR      = 0x0007,
+    OR      = 0x1007,
-    XOR     = 0x0008,
+    XOR     = 0x1008,
-    SHL     = 0x0009,
+    SHL     = 0x1009,
-    SHR     = 0x000a,
+    SHR     = 0x100a,
-    INEG    = 0x000b,
+    INEG    = 0x100b,
-    INV     = 0x000c,
+    INV     = 0x100c,
-    NOT     = 0x000d,
+    NOT     = 0x100d,
-    CMPEQ   = 0x1000,
+    CMPEQ   = 0x2000,
-    CMPLT   = 0x1001,
+    CMPLT   = 0x2001,
-    JMP     = 0x1002,
+    JMP     = 0x2002,
-    JZ      = 0x1003,
+    JZ      = 0x2003,
-    JNZ     = 0x1004,
+    JNZ     = 0x2004,
-    CALL    = 0x2000,
+    CALL    = 0x3000,
-    RET     = 0x2001,
+    RET     = 0x3001,
-    PUSH    = 0x2002,
+    PUSH    = 0x3002,
-    POP     = 0x2003,
+    POP     = 0x3003,
-    INT     = 0x2004,
+    INT     = 0x3004,
-    IRET    = 0x2005,
+    IRET    = 0x3005,
-    MOV     = 0x3000,
+    MOV     = 0x4000,
     HALT    = 0xF000,
     NOP     = 0xF001,
     DUMP    = 0xF002,

src/libvm/src/obj/assemble/session.rs

@@ -1,5 +1,4 @@
 use crate::{
-    addr::Addr,
     obj::{
         assemble::{
             Asm,

src/libvm/src/obj/disassemble.rs

@@ -1,4 +1,4 @@
-use crate::{mem::MemCursor, obj::obj::*, inst::Inst};
+use crate::{mem::MemCursor, obj::obj::*};
 use prettytable::{Table, row, cell};
 use std::io::{self, Write as Write};
 

src/main.rs

@@ -4,7 +4,7 @@ extern crate libvm as vm;
 
 use structopt::StructOpt;
 use snafu::Snafu;
-use std::{fs, io::{stdin, stdout, Write, Read}, path::{Path, PathBuf}, process};
+use std::{fs, io::{stdout, Write}, path::{Path, PathBuf}, process};
 
 const DEFAULT_MAX_MEM: usize = 64 * 1024 * 1024;
 

vm.md

@@ -128,43 +128,43 @@ Arithmetic instructions store their result in the first register specified. Over
 wrapping around to 0.
 
 * Add
-    * Opcode: 0x0000
+    * Opcode: 0x1000
     * Params: Destination, source
 * Sub
-    * Opcode: 0x0001
+    * Opcode: 0x1001
     * Params: Destination, source
 * Mul
-    * Opcode: 0x0002
+    * Opcode: 0x1002
     * Params: Destination, source
 * Div
-    * Opcode: 0x0003
+    * Opcode: 0x1003
     * Params: Destination, source
 * Mod
-    * Opcode: 0x0004
+    * Opcode: 0x1004
     * Params: Destination, source
 * And
-    * Opcode: 0x0005
+    * Opcode: 0x1005
     * Params: Destination, source
 * Or
-    * Opcode: 0x0006
+    * Opcode: 0x1006
     * Params: Destination, source
 * Xor
-    * Opcode: 0x0007
+    * Opcode: 0x1007
     * Params: Destination, source
 * Shl
-    * Opcode: 0x0008
+    * Opcode: 0x1008
     * Params: Destination, source
 * Shr
-    * Opcode: 0x0009
+    * Opcode: 0x1009
     * Params: Destination, source
 * INeg
-    * Opcode: 0x000a
+    * Opcode: 0x100a
     * Params: Destination, source
 * Inv
-    * Opcode: 0x000b
+    * Opcode: 0x100b
     * Params: Destination, source
 * Not
-    * Opcode: 0x000c
+    * Opcode: 0x100c
     * Params: Destination, source
 
 ### TODO
@@ -176,25 +176,25 @@ wrapping around to 0.
 ## Control flow
 
 * CmpEq
-    * Opcode: 0x1000
+    * Opcode: 0x2000
     * Params: Source, source
 * CmpLt
-    * Opcode: 0x1001
+    * Opcode: 0x2001
     * Params: Source, source
 * Jmp
-    * Opcode: 0x1002
+    * Opcode: 0x2002
     * Params: Source
 * Jz
-    * Opcode: 0x1003
+    * Opcode: 0x2003
     * Params: Source
 * Jnz
-    * Opcode: 0x1004
+    * Opcode: 0x2004
     * Params: Source
 
 ## Functions
 
 * Call
-    * Opcode: 0x2000
+    * Opcode: 0x3000
     * Params: Source
     * When this instruction is executed, these actions occur:
         * Push the current stack frame pointer
@@ -202,26 +202,26 @@ wrapping around to 0.
         * Update the IP (i.e., jump) to the value at the given source.
         * Update the frame pointer to the current stack pointer - 16
 * Ret
-    * Opcode: 0x2001
+    * Opcode: 0x3001
     * When this instruction is executed, these actions occur:
         * Update the stack pointer to the current frame pointer + 16.
         * Pop the IP of the next instruction.
         * Pop the old stack frame.
         * Restore the last three values in an undefined order
 * Push
-    * Opcode: 0x2002
+    * Opcode: 0x3002
     * Params: Source
     * When this instruction is executed, these actions occur:
         * Set the value in memory at the current stack pointer to the source value.
         * Increment the stack pointer by the size of value at the source.
 * Pop
-    * Opcode: 0x2003
+    * Opcode: 0x3003
     * Params: Dest
     * When this instruction is executed, these actions occur:
         * Decrement the stack pointer by the size of value at the destination.
         * Copy the value at the stack pointer into the destination.
 * Int
-    * Opcode: 0x2004
+    * Opcode: 0x3004
     * Params: Source, Source
     * When this instruction is executed, these actions occur:
         * Push the current stack frame pointer
@@ -235,7 +235,7 @@ wrapping around to 0.
         * Update the R1 register to the value in the second parameter
         * Update the frame pointer to the current stack pointer - 48
 * IRet
-    * Opcode: 0x2005
+    * Opcode: 0x3005
     * When this instruction is executed, these actions occur:
         * Update the stack pointer to the current frame pointer + 48
         * Pop the old R1 value
@@ -249,7 +249,7 @@ wrapping around to 0.
 ## Data movement
 
 * Mov
-    * Opcode: 0x3000
+    * Opcode: 0x4000
     * Params: Source, Dest
 
 ## Miscellaneous
@@ -410,7 +410,6 @@ A VM must provide support for the following meta-values:
 
 # General TODO
 
-* Interrupts
 * MMIO regions
 * Paging?
 * Determine how address sizes are determined