Function valueToTop

protocol/txbuilder/template.go:741–771

(b *txvmutil.Builder, stack []stackItem, amount int64, assetID bc.Hash)

}

func valueToTop(b *txvmutil.Builder, stack []stackItem, amount int64, assetID bc.Hash) ([]stackItem, error) {
	if len(stack) == 0 {
		return nil, errors.New("empty stack")
	}
	for {
		top := stack[len(stack)-1]
		if top.amount > 0 && top.assetID == assetID {
			if top.amount == amount {
				return stack, nil
			}
			if top.amount > amount {
				// con stack is [... val(orig - amount) val(amount)]
				return split(b, stack, amount), nil
			}
			if len(stack) > 1 {
				second := stack[len(stack)-2]
				if second.amount > 0 && second.assetID == assetID {
					stack = merge(b, stack, amount)
					continue
				}
			}
		}

		stack = findAndRoll(b, stack, func(i int, item stackItem) bool {
			return i != len(stack)-1 && item.amount > 0 && item.assetID == assetID
		})
		if stack == nil {
			return nil, errors.WithDetailf(ErrInsufficientValue, "amount=%d, assetID=%x", amount, assetID.Bytes())
		}
	}
}