neoneo-go/pkg/vm/vm_ops_maths.go

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package vm
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import (
"github.com/CityOfZion/neo-go/pkg/vm/stack"
)
// Add adds two stack Items together.
// Returns an error if either items cannot be casted to an integer
// or if integers cannot be added together
func Add(op stack.Instruction, ctx *stack.Context, istack *stack.Invocation, rstack *stack.RandomAccess) (Vmstate, error) {
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operandA, operandB, err := popTwoIntegers(ctx)
if err != nil {
return FAULT, err
}
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res, err := operandA.Add(operandB)
if err != nil {
return FAULT, err
}
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ctx.Estack.Push(res)
return NONE, nil
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}
// Sub subtracts two stack Items.
// Returns an error if either items cannot be casted to an integer
// or if integers cannot be subtracted together
func Sub(op stack.Instruction, ctx *stack.Context, istack *stack.Invocation, rstack *stack.RandomAccess) (Vmstate, error) {
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operandA, operandB, err := popTwoIntegers(ctx)
if err != nil {
return FAULT, err
}
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res, err := operandB.Sub(operandA)
if err != nil {
return FAULT, err
}
ctx.Estack.Push(res)
return NONE, nil
}
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func popTwoIntegers(ctx *stack.Context) (*stack.Int, *stack.Int, error) {
operandA, err := ctx.Estack.PopInt()
if err != nil {
return nil, nil, err
}
operandB, err := ctx.Estack.PopInt()
if err != nil {
return nil, nil, err
}
return operandA, operandB, nil
}
func popTwoByteArrays(ctx *stack.Context) (*stack.ByteArray, *stack.ByteArray, error) {
// Pop first stack item and cast as byte array
ba1, err := ctx.Estack.PopByteArray()
if err != nil {
return nil, nil, err
}
// Pop second stack item and cast as byte array
ba2, err := ctx.Estack.PopByteArray()
if err != nil {
return nil, nil, err
}
return ba1, ba2, nil
}