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use crate::error::Error;
use anyhow::{anyhow, Result};
use scroll::Pread;
/// An interface to be implemented for drivers that allow target memory access.
pub trait MemoryInterface {
/// Does this interface support native 64-bit wide accesses
///
/// If false all 64-bit operations may be split into 32 or 8 bit operations.
/// Most callers will not need to pivot on this but it can be useful for
/// picking the fastest bulk data transfer method.
fn supports_native_64bit_access(&mut self) -> bool;
/// Read a 64bit word of at `address`.
///
/// The address where the read should be performed at has to be word aligned.
/// Returns `AccessPortError::MemoryNotAligned` if this does not hold true.
fn read_word_64(&mut self, address: u64) -> Result<u64, Error>;
/// Read a 32bit word of at `address`.
///
/// The address where the read should be performed at has to be word aligned.
/// Returns [`Error::MemoryNotAligned`] if this does not hold true.
fn read_word_32(&mut self, address: u64) -> Result<u32, Error>;
/// Read an 8bit word of at `address`.
fn read_word_8(&mut self, address: u64) -> Result<u8, Error>;
/// Read a block of 64bit words at `address`.
///
/// The number of words read is `data.len()`.
/// The address where the read should be performed at has to be word aligned.
/// Returns [`Error::MemoryNotAligned`] if this does not hold true.
fn read_64(&mut self, address: u64, data: &mut [u64]) -> Result<(), Error>;
/// Read a block of 32bit words at `address`.
///
/// The number of words read is `data.len()`.
/// The address where the read should be performed at has to be word aligned.
/// Returns [`Error::MemoryNotAligned`] if this does not hold true.
fn read_32(&mut self, address: u64, data: &mut [u32]) -> Result<(), Error>;
/// Read a block of 8bit words at `address`.
fn read_8(&mut self, address: u64, data: &mut [u8]) -> Result<(), Error>;
/// Reads bytes using 64 bit memory access. Address must be 64 bit aligned
/// and data must be an exact multiple of 8.
fn read_mem_64bit(&mut self, address: u64, data: &mut [u8]) -> Result<(), Error> {
// Default implementation uses `read_64`, then converts u64 values back
// to bytes. Assumes target is little endian. May be overridden to
// provide an implementation that avoids heap allocation and endian
// conversions. Must be overridden for big endian targets.
if data.len() % 8 != 0 {
return Err(Error::Other(anyhow!(
"Call to read_mem_64bit with data.len() not a multiple of 8"
)));
}
let mut buffer = vec![0u64; data.len() / 8];
self.read_64(address, &mut buffer)?;
for (bytes, value) in data.chunks_exact_mut(8).zip(buffer.iter()) {
bytes.copy_from_slice(&u64::to_le_bytes(*value));
}
Ok(())
}
/// Reads bytes using 32 bit memory access. Address must be 32 bit aligned
/// and data must be an exact multiple of 4.
fn read_mem_32bit(&mut self, address: u64, data: &mut [u8]) -> Result<(), Error> {
// Default implementation uses `read_32`, then converts u32 values back
// to bytes. Assumes target is little endian. May be overridden to
// provide an implementation that avoids heap allocation and endian
// conversions. Must be overridden for big endian targets.
if data.len() % 4 != 0 {
return Err(Error::Other(anyhow!(
"Call to read_mem_32bit with data.len() not a multiple of 4"
)));
}
let mut buffer = vec![0u32; data.len() / 4];
self.read_32(address, &mut buffer)?;
for (bytes, value) in data.chunks_exact_mut(4).zip(buffer.iter()) {
bytes.copy_from_slice(&u32::to_le_bytes(*value));
}
Ok(())
}
/// Read data from `address`.
///
/// This function tries to use the fastest way of reading data, so there is no
/// guarantee which kind of memory access is used. The function might also read more
/// data than requested, e.g. when the start address is not aligned to a 32-bit boundary.
///
/// For more control, the `read_x` functiongs, e.g. [`MemoryInterface::read_32()`], can be
/// used.
///
/// Generally faster than `read_8`.
fn read(&mut self, address: u64, data: &mut [u8]) -> Result<(), Error> {
if self.supports_native_64bit_access() && address % 8 == 0 && data.len() % 8 == 0 {
// Avoid heap allocation and copy if we don't need it.
self.read_mem_64bit(address, data)?;
} else if address % 4 == 0 && data.len() % 4 == 0 {
// Avoid heap allocation and copy if we don't need it.
self.read_mem_32bit(address, data)?;
} else {
let start_extra_count = (address % 4) as usize;
let mut buffer = vec![0u8; (start_extra_count + data.len() + 3) / 4 * 4];
self.read_mem_32bit(address - start_extra_count as u64, &mut buffer)?;
data.copy_from_slice(&buffer[start_extra_count..start_extra_count + data.len()]);
}
Ok(())
}
/// Write a 64bit word at `address`.
///
/// The address where the write should be performed at has to be word aligned.
/// Returns [`Error::MemoryNotAligned`] if this does not hold true.
fn write_word_64(&mut self, address: u64, data: u64) -> Result<(), Error>;
/// Write a 32bit word at `address`.
///
/// The address where the write should be performed at has to be word aligned.
/// Returns [`Error::MemoryNotAligned`] if this does not hold true.
fn write_word_32(&mut self, address: u64, data: u32) -> Result<(), Error>;
/// Write an 8bit word at `address`.
fn write_word_8(&mut self, address: u64, data: u8) -> Result<(), Error>;
/// Write a block of 64bit words at `address`.
///
/// The number of words written is `data.len()`.
/// The address where the write should be performed at has to be word aligned.
/// Returns [`Error::MemoryNotAligned`] if this does not hold true.
fn write_64(&mut self, address: u64, data: &[u64]) -> Result<(), Error>;
/// Write a block of 32bit words at `address`.
///
/// The number of words written is `data.len()`.
/// The address where the write should be performed at has to be word aligned.
/// Returns [`Error::MemoryNotAligned`] if this does not hold true.
fn write_32(&mut self, address: u64, data: &[u32]) -> Result<(), Error>;
/// Write a block of 8bit words at `address`.
fn write_8(&mut self, address: u64, data: &[u8]) -> Result<(), Error>;
/// Writes bytes using 64 bit memory access. Address must be 64 bit aligned
/// and data must be an exact multiple of 8.
fn write_mem_64bit(&mut self, address: u64, data: &[u8]) -> Result<(), Error> {
// Default implementation uses `write_64`, then converts u64 values back
// to bytes. Assumes target is little endian. May be overridden to
// provide an implementation that avoids heap allocation and endian
// conversions. Must be overridden for big endian targets.
if data.len() % 8 != 0 {
return Err(Error::Other(anyhow!(
"Call to read_mem_64bit with data.len() not a multiple of 8"
)));
}
let mut buffer = vec![0u64; data.len() / 8];
for (bytes, value) in data.chunks_exact(8).zip(buffer.iter_mut()) {
*value = bytes
.pread_with(0, scroll::LE)
.expect("an u64 - this is a bug, please report it");
}
self.write_64(address, &buffer)?;
Ok(())
}
/// Writes bytes using 32 bit memory access. Address must be 32 bit aligned
/// and data must be an exact multiple of 8.
fn write_mem_32bit(&mut self, address: u64, data: &[u8]) -> Result<(), Error> {
// Default implementation uses `write_32`, then converts u32 values back
// to bytes. Assumes target is little endian. May be overridden to
// provide an implementation that avoids heap allocation and endian
// conversions. Must be overridden for big endian targets.
if data.len() % 4 != 0 {
return Err(Error::Other(anyhow!(
"Call to read_mem_32bit with data.len() not a multiple of 4"
)));
}
let mut buffer = vec![0u32; data.len() / 4];
for (bytes, value) in data.chunks_exact(4).zip(buffer.iter_mut()) {
*value = bytes
.pread_with(0, scroll::LE)
.expect("an u32 - this is a bug, please report it");
}
self.write_32(address, &buffer)?;
Ok(())
}
/// Write a block of 8bit words at `address`. May use 64 bit memory access,
/// so should only be used if reading memory locations that don't have side
/// effects. Generally faster than [`MemoryInterface::write_8`].
///
/// If the target does not support 8-bit aligned access, and `address` is not
/// aligned on a 32-bit boundary, this function will return a [`Error::MemoryNotAligned`] error.
fn write(&mut self, address: u64, data: &[u8]) -> Result<(), Error> {
let len = data.len();
let start_extra_count = 4 - (address % 4) as usize;
let end_extra_count = (len - start_extra_count) % 4;
let inbetween_count = len - start_extra_count - end_extra_count;
assert!(start_extra_count < 4);
assert!(end_extra_count < 4);
assert!(inbetween_count % 4 == 0);
// If we do not have 32 bit aligned access we first check that we can do 8 bit aligned access on this platform.
// If we cannot we throw an error.
// If we can we read the first n < 4 bytes up until the word aligned address that comes next.
if address % 4 != 0 || len % 4 != 0 {
// If we do not support 8 bit transfers we have to bail because we can only do 32 bit word aligned transers.
if !self.supports_8bit_transfers()? {
return Err(Error::MemoryNotAligned {
address,
alignment: 4,
});
}
// We first do an 8 bit write of the first < 4 bytes up until the 4 byte aligned boundary.
self.write_8(address, &data[..start_extra_count])?;
}
let mut buffer = vec![0u32; inbetween_count / 4];
for (bytes, value) in data.chunks_exact(4).zip(buffer.iter_mut()) {
*value = u32::from_le_bytes([bytes[0], bytes[1], bytes[2], bytes[3]]);
}
self.write_32(address, &buffer)?;
// We read the remaining bytes that we did not read yet which is always n < 4.
if end_extra_count > 0 {
self.write_8(address, &data[..start_extra_count])?;
}
Ok(())
}
/// Returns whether the current platform supports native 8bit transfers.
fn supports_8bit_transfers(&self) -> Result<bool, Error>;
/// Flush any outstanding operations.
///
/// For performance, debug probe implementations may choose to batch writes;
/// to assure that any such batched writes have in fact been issued, `flush`
/// can be called. Takes no arguments, but may return failure if a batched
/// operation fails.
fn flush(&mut self) -> Result<(), Error>;
}
impl<T> MemoryInterface for &mut T
where
T: MemoryInterface,
{
fn supports_native_64bit_access(&mut self) -> bool {
(*self).supports_native_64bit_access()
}
fn read_word_64(&mut self, address: u64) -> Result<u64, Error> {
(*self).read_word_64(address)
}
fn read_word_32(&mut self, address: u64) -> Result<u32, Error> {
(*self).read_word_32(address)
}
fn read_word_8(&mut self, address: u64) -> Result<u8, Error> {
(*self).read_word_8(address)
}
fn read_64(&mut self, address: u64, data: &mut [u64]) -> Result<(), Error> {
(*self).read_64(address, data)
}
fn read_32(&mut self, address: u64, data: &mut [u32]) -> Result<(), Error> {
(*self).read_32(address, data)
}
fn read_8(&mut self, address: u64, data: &mut [u8]) -> Result<(), Error> {
(*self).read_8(address, data)
}
fn read(&mut self, address: u64, data: &mut [u8]) -> Result<(), Error> {
(*self).read(address, data)
}
fn write_word_64(&mut self, address: u64, data: u64) -> Result<(), Error> {
(*self).write_word_64(address, data)
}
fn write_word_32(&mut self, address: u64, data: u32) -> Result<(), Error> {
(*self).write_word_32(address, data)
}
fn write_word_8(&mut self, address: u64, data: u8) -> Result<(), Error> {
(*self).write_word_8(address, data)
}
fn write_64(&mut self, address: u64, data: &[u64]) -> Result<(), Error> {
(*self).write_64(address, data)
}
fn write_32(&mut self, address: u64, data: &[u32]) -> Result<(), Error> {
(*self).write_32(address, data)
}
fn write_8(&mut self, address: u64, data: &[u8]) -> Result<(), Error> {
(*self).write_8(address, data)
}
fn write(&mut self, address: u64, data: &[u8]) -> Result<(), Error> {
(*self).write(address, data)
}
fn supports_8bit_transfers(&self) -> Result<bool, Error> {
MemoryInterface::supports_8bit_transfers(*self)
}
fn flush(&mut self) -> Result<(), Error> {
(*self).flush()
}
}
// Helper functions to validate address space constraints
/// Validate that an input address is valid for 32-bit only systems
pub(crate) fn valid_32bit_address(address: u64) -> Result<u32, Error> {
let address: u32 = address
.try_into()
.map_err(|_| anyhow!("Address {:#08x} out of range", address))?;
Ok(address)
}