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(ctx *stack.Context, istack *stack.Invocation) error {
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operandA, operandB, err := popTwoIntegers(ctx)
res, err := operandA.Add(operandB)
if err != nil {
return err
}
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ctx.Estack.Push(res)
return nil
}
// 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(ctx *stack.Context, istack *stack.Invocation) error {
operandA, operandB, err := popTwoIntegers(ctx)
res, err := operandB.Sub(operandA)
if err != nil {
return err
}
ctx.Estack.Push(res)
return 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
}