Updated documentation and instruction set

vvm/README.md

@@ -3,3 +3,52 @@ Veits Virtual Machine
 
 A virtual machine that executes assembler-like code.
 
+
+Instruction set
+---------------
+
+Up until now, all the operations are executed on integers(hence the
+I\* prefix).
+
+IADD - Adds the two items to each other that are on top of the stack
+and stores the result on top of the stack.
+ISUB - Subtracts the two items from each other that are on top of the
+stack and stores the result on top of the stack.
+IMULT - Multiplies the two items to each other that are on top of the
+stack and stores the result on top of the stack.
+IDIV - Performs a division operation to the two items that are on top 
+of the stack and stores the result on top of the stack.
+IMOD - Performs a modulo operation to the two items that are on top 
+of the stack and stores the result on top of the stack.
+ILT - Checks whether the item on top of the stack is greater than the
+item below it and stores a boolean on top of the stack.
+IEQ - Checks whether the item on top of the stack is equal to the
+item below it and stores a boolean on top of the stack.
+IGT - Checks whether the item on top of the stack is smaller than the
+item below it and stores a boolean on top of the stack.
+ILEQ - Checks whether the item on top of the stack is smaller than or 
+equal to the item below it and stores a boolean on top of the stack.
+IGEQ - Checks whether the item on top of the stack is greater than or 
+equal to the item below it and stores a boolean on top of the stack.
+BR - Jumps to the instruction that is provided as an argument.
+BRT - Jumps to the instruction that is provided as an argument if the
+value on top of the stack is TRUE.
+BRF - Jumps to the instruction that is provided as an argument if the
+value on top of the stack is FALSE.
+ICONST - Puts the argument provided to the operation on top of the 
+stack.
+LOAD - Loads an element from any position on the stack on top of the
+stack(usually used to get function arguments like this: LOAD -3).
+GLOAD - Loads an element from any position on the data segment  on 
+top of the stack.
+STORE - Stores an element on the stack.
+GSTORE - Stores an element in the data segment.
+PRINT - Prints the element on top of the stack as character.
+IPRINT - Prints the element on top of the stack as integer.
+POP - Pops the element on top of the stack.
+HALT - Ends the program.
+CALL - calls a subroutine with a number of arguments.
+RET - Returns from a subroutine with a return value.
+FETCH - Fetches a value.
+IINC -Increments the value on top of the stack by one(equal to ++).
+IDEC -Decrements the value on top of the stack by one(equal to --).

vvm/src/opcode.c

@@ -4,7 +4,7 @@
 
 const char* opcodes[] = {"IADD", "ISUB", "IMULT", "IDIV", "IMOD",
     "ILT", "IEQ", "IGT", "BR", "BRT", "BRF", "ICONST", "LOAD", "GLOAD",
-    "STORE", "GSTORE", "PRINT", "POP", "HALT", "LEQ", "GEQ", "CALL", "RET",
+    "STORE", "GSTORE", "PRINT", "POP", "HALT", "ILEQ", "IGEQ", "CALL", "RET",
     "IPRINT", "FETCH", "IINC", "IDEC" };
 
 int nargs[] = { 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 

vvm/src/opcode.h

@@ -19,8 +19,8 @@
 #define PRINT 17
 #define POP 18
 #define HALT 19
-#define LEQ 20
-#define GEQ 21
+#define ILEQ 20
+#define IGEQ 21
 #define CALL 22
 #define RET 23
 #define IPRINT 24