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fix rom_table_lookup

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It seems like the rom_table_lookup missed one level of
pointer dereferencing.

After comparing it to the working call to reset_usb_boot() in
https://github.com/jannic/rp-microcontroller-rs/blob/master/util/rp2040-panic-usb-boot/src/lib.rs,
I changed the code until it generated basically the same assembly.

With that change, I was able to successfully call rom_data::reset_to_usb_boot()

I still don't like the type RomTableLookupFn, which just returns
some generic T without any checks, and I think rom_table_lookup
should be unsafe. But as none of those are pub, it doesn't matter too
much. So I just made the changes necessary to make the code work.
This commit is contained in:
Jan Niehusmann 2021-02-15 22:16:43 +00:00
parent be7dd11057
commit d6231bd3ec
1 changed files with 11 additions and 5 deletions
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16
rp2040-hal/src/rom_data.rs
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@ -11,19 +11,25 @@ type RomTableLookupFn<T> = unsafe extern "C" fn(*const u16, u32) -> T;
const ROM_TABLE_LOOKUP_PTR: *const u16 = 0x18 as _;
/// Pointer to helper functions lookup table.
const FUNC_TABLE: *const *const u16 = 0x14 as _;
const FUNC_TABLE: *const u16 = 0x14 as _;
/// Pointer to the public data lookup table.
const DATA_TABLE: *const *const u16 = 0x16 as _;
const DATA_TABLE: *const u16 = 0x16 as _;
/// Retrive rom content from a table using a code.
fn rom_table_lookup<T>(table: *const *const u16, tag: RomFnTableCode) -> T {
fn rom_table_lookup<T>(table: *const u16, tag: RomFnTableCode) -> T {
unsafe {
let rom_table_lookup: RomTableLookupFn<T> = core::mem::transmute(ROM_TABLE_LOOKUP_PTR);
rom_table_lookup(*table, u16::from_le_bytes(tag) as u32)
let rom_table_lookup_ptr: *const u32 = rom_hword_as_ptr(ROM_TABLE_LOOKUP_PTR);
let rom_table_lookup: RomTableLookupFn<T> = core::mem::transmute(rom_table_lookup_ptr);
rom_table_lookup(rom_hword_as_ptr(table) as *const u16, u16::from_le_bytes(tag) as u32)
}
}
unsafe fn rom_hword_as_ptr(rom_address: *const u16) -> *const u32 {
let ptr: u16 = *rom_address;
ptr as *const u32
}
macro_rules! rom_funcs {
(
$(