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Updated documentation and instruction set

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Veit Heller
2014-07-26 20:35:49 +02:00
parent 2253d2729a
commit 55b0dc1a77
3 changed files with 52 additions and 3 deletions
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49
vvm/README.md
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@@ -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 --).

2
vvm/src/opcode.c
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@@ -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,

4
vvm/src/opcode.h
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@@ -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