use crate::{
cost_model::transferred_byte_cycles,
syscalls::{
utils::store_data, InputField, Source, SourceEntry, INDEX_OUT_OF_BOUND,
LOAD_INPUT_BY_FIELD_SYSCALL_NUMBER, LOAD_INPUT_SYSCALL_NUMBER, SUCCESS,
},
};
use byteorder::{LittleEndian, WriteBytesExt};
use ckb_types::{
packed::{CellInput, CellInputVec},
prelude::*,
};
use ckb_vm::{
registers::{A0, A3, A4, A5, A7},
Error as VMError, Register, SupportMachine, Syscalls,
};
#[derive(Debug)]
pub struct LoadInput<'a> {
inputs: CellInputVec,
group_inputs: &'a [usize],
}
impl<'a> LoadInput<'a> {
pub fn new(inputs: CellInputVec, group_inputs: &'a [usize]) -> LoadInput<'a> {
LoadInput {
inputs,
group_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
.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().unpack())?;
store_data(machine, &buffer)
}
}
}
}
impl<'a, Mac: SupportMachine> Syscalls<Mac> for LoadInput<'a> {
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 as u64))?;
machine.set_register(A0, Mac::REG::from_u8(SUCCESS));
Ok(true)
}
}