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rom: Change rom_table_lookup to use the rom's built in one

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This commit is contained in:
Asaf Fisher 2021-02-03 02:15:45 +02:00
parent 1c75ed3844
commit 6eccce595c
1 changed files with 17 additions and 15 deletions
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32
rp2040-hal/src/rom_data.rs
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@ -1,24 +1,26 @@
//! Functions and data from the RPI Bootrom.
/// A bootrom function table code.
pub type RomFnTableCode = [u8; 2];
/// This function searches for (table)
type RomTableLookupFn<T> = unsafe extern "C" fn(*const u16, u32) -> T;
/// The following addresses are described at `2.8.3. Bootrom Contents`
/// Pointer to the lookup table function supplied by the rom.
const ROM_TABLE_LOOKUP_PTR: *const u16 = 0x18 as _;
/// Pointer to helper functions lookup table.
const FUNC_TABLE: *const *const u16 = 0x14 as _;
/// Pointer to the public data lookup table.
const DATA_TABLE: *const *const u16 = 0x16 as _;
fn rom_table_lookup<T>(table: *const *const u16, tag: [u8; 2]) -> T {
let tag = u16::from_le_bytes(tag);
/// Retrive rom content from a table using a code.
fn rom_table_lookup<T>(table: *const *const u16, tag: RomFnTableCode) -> T {
unsafe {
let mut entry = *table;
loop {
let entry_tag = entry.read();
if entry_tag == 0 {
panic!("not found");
}
entry = entry.add(1);
let entry_addr = entry.read();
if entry_tag == tag {
break core::mem::transmute_copy(&entry_addr);
}
entry = entry.add(1);
}
let rom_table_lookup: RomTableLookupFn<T> = core::mem::transmute(ROM_TABLE_LOOKUP_PTR);
rom_table_lookup(*table, u16::from_le_bytes(tag) as u32)
}
}