ckb-script 1.1.0

use crate::{
    cost_model::transferred_byte_cycles,
    syscalls::{
        INDEX_OUT_OF_BOUND, InputField, LOAD_INPUT_BY_FIELD_SYSCALL_NUMBER,
        LOAD_INPUT_SYSCALL_NUMBER, SUCCESS, Source, SourceEntry, utils::store_data,
    },
    types::SgData,
};
use byteorder::{LittleEndian, WriteBytesExt};
use ckb_types::{
    packed::{CellInput, CellInputVec},
    prelude::*,
};
use ckb_vm::{
    Error as VMError, Register, SupportMachine, Syscalls,
    registers::{A0, A3, A4, A5, A7},
};

#[derive(Debug)]
pub struct LoadInput<DL> {
    sg_data: SgData<DL>,
}

impl<DL: Clone> LoadInput<DL> {
    pub fn new(sg_data: &SgData<DL>) -> Self {
        LoadInput {
            sg_data: sg_data.clone(),
        }
    }

    #[inline]
    fn inputs(&self) -> CellInputVec {
        self.sg_data.rtx.transaction.inputs()
    }

    fn fetch_input(&self, source: Source, index: usize) -> Result<CellInput, u8> {
        match source {
            Source::Transaction(SourceEntry::Input) => {
                self.inputs().get(index).ok_or(INDEX_OUT_OF_BOUND)
            }
            Source::Transaction(SourceEntry::Output) => Err(INDEX_OUT_OF_BOUND),
            Source::Transaction(SourceEntry::CellDep) => Err(INDEX_OUT_OF_BOUND),
            Source::Transaction(SourceEntry::HeaderDep) => Err(INDEX_OUT_OF_BOUND),
            Source::Group(SourceEntry::Input) => self
                .sg_data
                .group_inputs()
                .get(index)
                .ok_or(INDEX_OUT_OF_BOUND)
                .and_then(|actual_index| {
                    self.inputs().get(*actual_index).ok_or(INDEX_OUT_OF_BOUND)
                }),
            Source::Group(SourceEntry::Output) => Err(INDEX_OUT_OF_BOUND),
            Source::Group(SourceEntry::CellDep) => Err(INDEX_OUT_OF_BOUND),
            Source::Group(SourceEntry::HeaderDep) => Err(INDEX_OUT_OF_BOUND),
        }
    }

    fn load_full<Mac: SupportMachine>(
        &self,
        machine: &mut Mac,
        input: &CellInput,
    ) -> Result<u64, VMError> {
        let data = input.as_slice();
        let wrote_size = store_data(machine, data)?;
        Ok(wrote_size)
    }

    fn load_by_field<Mac: SupportMachine>(
        &self,
        machine: &mut Mac,
        input: &CellInput,
    ) -> Result<u64, VMError> {
        let field = InputField::parse_from_u64(machine.registers()[A5].to_u64())?;

        match field {
            InputField::OutPoint => {
                let previous_output = input.previous_output();
                let data = previous_output.as_slice();
                store_data(machine, data)
            }
            InputField::Since => {
                let mut buffer = vec![];
                buffer.write_u64::<LittleEndian>(input.since().into())?;
                store_data(machine, &buffer)
            }
        }
    }
}

impl<Mac: SupportMachine, DL: Send + Sync + Clone> Syscalls<Mac> for LoadInput<DL> {
    fn initialize(&mut self, _machine: &mut Mac) -> Result<(), VMError> {
        Ok(())
    }

    fn ecall(&mut self, machine: &mut Mac) -> Result<bool, VMError> {
        let load_by_field = match machine.registers()[A7].to_u64() {
            LOAD_INPUT_SYSCALL_NUMBER => false,
            LOAD_INPUT_BY_FIELD_SYSCALL_NUMBER => true,
            _ => return Ok(false),
        };

        let index = machine.registers()[A3].to_u64();
        let source = Source::parse_from_u64(machine.registers()[A4].to_u64())?;

        let input = self.fetch_input(source, index as usize);
        if let Err(err) = input {
            machine.set_register(A0, Mac::REG::from_u8(err));
            return Ok(true);
        }
        let input = input.unwrap();

        let len = if load_by_field {
            self.load_by_field(machine, &input)?
        } else {
            self.load_full(machine, &input)?
        };

        machine.add_cycles_no_checking(transferred_byte_cycles(len))?;
        machine.set_register(A0, Mac::REG::from_u8(SUCCESS));
        Ok(true)
    }
}