95 lines
2.6 KiB
Go
95 lines
2.6 KiB
Go
package vm
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import (
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"github.com/CityOfZion/neo-go/pkg/vm/stack"
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)
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// Flow control
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// RET Returns from the current context
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// Returns HALT if there are nomore context's to run
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func RET(op stack.Instruction, ctx *stack.Context, istack *stack.Invocation, rstack *stack.RandomAccess) (Vmstate, error) {
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// Pop current context from the Inovation stack
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ctx, err := istack.PopCurrentContext()
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if err != nil {
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return FAULT, err
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}
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// If this was the last context, then we copy over the evaluation stack to the resultstack
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// As the program is about to terminate, once we remove the context
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if istack.Len() == 0 {
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err = ctx.Estack.CopyTo(rstack)
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return HALT, err
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}
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return NONE, nil
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}
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// NOP Returns NONE VMState.
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func NOP(op stack.Instruction, ctx *stack.Context, istack *stack.Invocation, rstack *stack.RandomAccess) (Vmstate, error) {
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return NONE, nil
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}
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// JMP moves the instruction pointer to an offset which is
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// calculated base on the instructionPointerOffset method.
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// Returns and error if the offset is out of range.
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func JMP(op stack.Instruction, ctx *stack.Context, istack *stack.Invocation, rstack *stack.RandomAccess) (Vmstate, error) {
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offset := instructionPointerOffset(ctx)
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if err := ctx.SetIP(offset); err != nil {
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return FAULT, err
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}
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return NONE, nil
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}
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// JMPIF pops a boolean off of the stack and,
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// if the the boolean's value is true, it
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// moves the instruction pointer to an offset which is
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// calculated base on the instructionPointerOffset method.
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// Returns and error if the offset is out of range or
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// the popped item is not a boolean.
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func JMPIF(op stack.Instruction, ctx *stack.Context, istack *stack.Invocation, rstack *stack.RandomAccess) (Vmstate, error) {
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b, err := ctx.Estack.PopBoolean()
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if err != nil {
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return FAULT, err
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}
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if b.Value() {
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offset := instructionPointerOffset(ctx)
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if err := ctx.SetIP(offset); err != nil {
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return FAULT, err
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}
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}
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return NONE, nil
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}
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// JMPIFNOT pops a boolean off of the stack and,
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// if the the boolean's value is false, it
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// moves the instruction pointer to an offset which is
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// calculated base on the instructionPointerOffset method.
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// Returns and error if the offset is out of range or
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// the popped item is not a boolean.
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func JMPIFNOT(op stack.Instruction, ctx *stack.Context, istack *stack.Invocation, rstack *stack.RandomAccess) (Vmstate, error) {
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b, err := ctx.Estack.PopBoolean()
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if err != nil {
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return FAULT, err
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}
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if !b.Value() {
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offset := instructionPointerOffset(ctx)
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if err := ctx.SetIP(offset); err != nil {
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return FAULT, err
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}
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}
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return NONE, nil
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}
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func instructionPointerOffset(ctx *stack.Context) int {
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return ctx.IP() + int(ctx.ReadInt16()) - 3
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}
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