unleashed-firmware/lib/flipper_application/api_hashtable/api_hashtable.h
Sergey Gavrilov 645a7c5989
[FL-3386] Fast FAP Loader (#2790)
* FBT: build and add FastFAP(tm) sections
* Elf file: fast loading fap files. Really fast, like x15 times faster.
* fastfap.py: cleanup unused imports
* Toolchain: 23 version
* Elf File: remove log messages
* Scripts: fix file permissions
* FBT: explicit interpreter for fastfap invocation

Co-authored-by: あく <alleteam@gmail.com>
2023-06-28 17:19:10 +09:00

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2.3 KiB
C++

#pragma once
#include <flipper_application/elf/elf_api_interface.h>
#include <stdint.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief Symbol table entry
*/
struct sym_entry {
uint32_t hash;
uint32_t address;
};
/**
* @brief Resolver for API entries using a pre-sorted table with hashes
* @param interface pointer to HashtableApiInterface
* @param hash gnu hash of function name
* @param address output for function address
* @return true if the table contains a function
*/
bool elf_resolve_from_hashtable(
const ElfApiInterface* interface,
uint32_t hash,
Elf32_Addr* address);
uint32_t elf_symbolname_hash(const char* s);
#ifdef __cplusplus
}
#include <array>
#include <algorithm>
/**
* @brief HashtableApiInterface is an implementation of ElfApiInterface
* that uses a hash table to resolve function addresses.
* table_cbegin and table_cend must point to a sorted array of sym_entry
*/
struct HashtableApiInterface : public ElfApiInterface {
const sym_entry *table_cbegin, *table_cend;
};
#define API_METHOD(x, ret_type, args_type) \
sym_entry { \
.hash = elf_gnu_hash(#x), .address = (uint32_t)(static_cast<ret_type(*) args_type>(x)) \
}
#define API_VARIABLE(x, var_type) \
sym_entry { \
.hash = elf_gnu_hash(#x), .address = (uint32_t)(&(x)), \
}
constexpr bool operator<(const sym_entry& k1, const sym_entry& k2) {
return k1.hash < k2.hash;
}
/**
* @brief Calculate hash for a string using the ELF GNU hash algorithm
* @param s string to calculate hash for
* @return hash value
*/
constexpr uint32_t elf_gnu_hash(const char* s) {
uint32_t h = 0x1505;
for(unsigned char c = *s; c != '\0'; c = *++s) {
h = (h << 5) + h + c;
}
return h;
}
/* Compile-time check for hash collisions in API table.
* Usage: static_assert(!has_hash_collisions(api_methods), "Hash collision detected");
*/
template <std::size_t N>
constexpr bool has_hash_collisions(const std::array<sym_entry, N>& api_methods) {
for(std::size_t i = 0; i < (N - 1); ++i) {
if(api_methods[i].hash == api_methods[i + 1].hash) {
return true;
}
}
return false;
}
#endif