esp-idf/components/esp_common/include/esp_attr.h

/*
 * SPDX-FileCopyrightText: 2015-2026 Espressif Systems (Shanghai) CO LTD
 *
 * SPDX-License-Identifier: Apache-2.0
 */
#ifndef __ESP_ATTR_H__
#define __ESP_ATTR_H__

#ifdef __cplusplus
extern "C" {
#endif

#include "sdkconfig.h"
#include "esp_assert.h"

#define ROMFN_ATTR

//Normally, the linker script will put all code and rodata in flash,
//and all variables in shared RAM. These macros can be used to redirect
//particular functions/variables to other memory regions.

// Places code into IRAM instead of flash
#define IRAM_ATTR _SECTION_ATTR_IMPL(".iram1", __COUNTER__)

// Forces code into IRAM instead of flash
#define FORCE_IRAM_ATTR _SECTION_FORCE_ATTR_IMPL(".iram1", __COUNTER__)

// Forces data into DRAM instead of flash
#define DRAM_ATTR _SECTION_ATTR_IMPL(".dram1", __COUNTER__)

// Places code into SPM instead of flash
#define SPM_IRAM_ATTR _SECTION_ATTR_IMPL(".spm.text", __COUNTER__)

// Forces code into SPM instead of flash
#define FORCE_SPM_IRAM_ATTR _SECTION_FORCE_ATTR_IMPL(".spm.text", __COUNTER__)

// Forces data into SPM instead of L2MEM
#define SPM_DRAM_ATTR _SECTION_ATTR_IMPL(".spm.data", __COUNTER__)

// Deprecated macros for TCM (SPM)
#define TCM_IRAM_ATTR _SECTION_ATTR_IMPL(".spm.text", __COUNTER__) _Pragma ("GCC warning \"'TCM_IRAM_ATTR' macro is deprecated, please use `SPM_IRAM_ATTR`\"")
#define FORCE_TCM_IRAM_ATTR _SECTION_FORCE_ATTR_IMPL(".spm.text", __COUNTER__) _Pragma ("GCC warning \"'FORCE_TCM_IRAM_ATTR' macro is deprecated, please use `FORCE_SPM_IRAM_ATTR`\"")
#define TCM_DRAM_ATTR _SECTION_ATTR_IMPL(".spm.data", __COUNTER__) _Pragma ("GCC warning \"'TCM_DRAM_ATTR' macro is deprecated, please use `SPM_DRAM_ATTR`\"")

// Forces data to be removed from the final binary but keeps it in the ELF file
#define NOLOAD_ATTR _SECTION_ATTR_IMPL(".noload_keep_in_elf", __COUNTER__)

// IRAM can only be accessed as an 8-bit memory on ESP32, when CONFIG_ESP32_IRAM_AS_8BIT_ACCESSIBLE_MEMORY is set
#define IRAM_8BIT_ACCESSIBLE (CONFIG_IDF_TARGET_ESP32 && CONFIG_ESP32_IRAM_AS_8BIT_ACCESSIBLE_MEMORY)

// Make sure that IRAM is accessible as an 8-bit memory on ESP32.
// If that's not the case, coredump cannot dump data from IRAM.
#if IRAM_8BIT_ACCESSIBLE
// Forces data into IRAM instead of DRAM
#define IRAM_DATA_ATTR __attribute__((section(".iram.data")))

// Forces data into IRAM instead of DRAM and map it to coredump
#define COREDUMP_IRAM_DATA_ATTR _SECTION_ATTR_IMPL(".iram2.coredump", __COUNTER__)

// Forces bss into IRAM instead of DRAM
#define IRAM_BSS_ATTR __attribute__((section(".iram.bss")))
#else

// IRAM is not accessible as an 8-bit memory, put IRAM coredump variables in DRAM
#define COREDUMP_IRAM_DATA_ATTR COREDUMP_DRAM_ATTR
#define IRAM_DATA_ATTR

#define IRAM_BSS_ATTR
#endif

// Forces data to be 4 bytes aligned
#define WORD_ALIGNED_ATTR __attribute__((aligned(4)))

// Forces data to be placed to DMA-capable places
#define DMA_ATTR WORD_ALIGNED_ATTR DRAM_ATTR

//Force data to be placed in DRAM and aligned according to DMA and cache's requirement
#if CONFIG_SOC_CACHE_INTERNAL_MEM_VIA_L1CACHE
#define DRAM_DMA_ALIGNED_ATTR __attribute__((aligned(CONFIG_CACHE_L1_CACHE_LINE_SIZE))) DRAM_ATTR
#else
#define DRAM_DMA_ALIGNED_ATTR WORD_ALIGNED_ATTR DRAM_ATTR
#endif

// Forces the data to be tightly packed with minimum required padding and no extra bytes are added for alignment
#define PACKED_ATTR __attribute__((packed))

// Forces a function to be inlined
#define FORCE_INLINE_ATTR static inline __attribute__((always_inline))

// Forces a string into DRAM instead of flash
// Use as esp_rom_printf(DRAM_STR("Hello world!\n"));
#define DRAM_STR(str) (__extension__({static const DRAM_ATTR char __c[] = (str); (const char *)&__c;}))

#if CONFIG_SOC_RTC_FAST_MEM_SUPPORTED || CONFIG_SOC_RTC_SLOW_MEM_SUPPORTED
// Forces data into RTC memory. See "docs/deep-sleep-stub.rst"
// Any variable marked with this attribute will keep its value
// during a deep sleep / wake cycle.
#define RTC_DATA_ATTR _SECTION_ATTR_IMPL(".rtc.data", __COUNTER__)

// Forces data into RTC memory of .noinit section.
// Any variable marked with this attribute will keep its value
// after restart or during a deep sleep / wake cycle.
#define RTC_NOINIT_ATTR  _SECTION_ATTR_IMPL(".rtc_noinit", __COUNTER__)

// Forces read-only data into RTC memory. See "docs/deep-sleep-stub.rst"
#define RTC_RODATA_ATTR _SECTION_ATTR_IMPL(".rtc.rodata", __COUNTER__)

// Forces data into RTC memory and map it to coredump
#define COREDUMP_RTC_DATA_ATTR _SECTION_ATTR_IMPL(".rtc.coredump", __COUNTER__)

// Allows to place data into RTC_SLOW memory.
#define RTC_SLOW_ATTR _SECTION_ATTR_IMPL(".rtc.force_slow", __COUNTER__)

// Forces code into RTC fast memory. See "docs/deep-sleep-stub.rst"
#define RTC_IRAM_ATTR _SECTION_ATTR_IMPL(".rtc.text", __COUNTER__)

// Allows to place data into RTC_FAST memory.
#define RTC_FAST_ATTR _SECTION_ATTR_IMPL(".rtc.force_fast", __COUNTER__)

// Allows to place data into RTC_FAST memory and map it to coredump
#define COREDUMP_RTC_FAST_ATTR _SECTION_ATTR_IMPL(".rtc.fast.coredump", __COUNTER__)

// Allows to place data into RTC_NOINIT memory and map it to coredump
#define COREDUMP_NOINIT_ATTR _SECTION_ATTR_IMPL(".rtc_noinit.coredump", __COUNTER__)
#else

// Allows to place data into NOINIT memory and map it to coredump
#define COREDUMP_NOINIT_ATTR _SECTION_ATTR_IMPL(".noinit.coredump", __COUNTER__)

// RTC memory is not supported on these chips
#define RTC_DATA_ATTR ESP_STATIC_ASSERT(0, "RTC_DATA_ATTR is not supported on this chip. Use DRAM_ATTR instead.")
#define RTC_NOINIT_ATTR ESP_STATIC_ASSERT(0, "RTC_NOINIT_ATTR is not supported on this chip. Use DRAM_ATTR instead.")
#define RTC_RODATA_ATTR ESP_STATIC_ASSERT(0, "RTC_RODATA_ATTR is not supported on this chip. Use DRAM_ATTR instead.")
#define COREDUMP_RTC_DATA_ATTR ESP_STATIC_ASSERT(0, "COREDUMP_RTC_DATA_ATTR is not supported on this chip. Use COREDUMP_DRAM_ATTR instead.")
#define RTC_SLOW_ATTR ESP_STATIC_ASSERT(0, "RTC_SLOW_ATTR is not supported on this chip. Use DRAM_ATTR instead.")
#define RTC_IRAM_ATTR ESP_STATIC_ASSERT(0, "RTC_IRAM_ATTR is not supported on this chip. Use IRAM_ATTR instead.")
#define RTC_FAST_ATTR ESP_STATIC_ASSERT(0, "RTC_FAST_ATTR is not supported on this chip. Use DRAM_ATTR instead.")
#define COREDUMP_RTC_FAST_ATTR ESP_STATIC_ASSERT(0, "COREDUMP_RTC_FAST_ATTR is not supported on this chip. Use COREDUMP_DRAM_ATTR instead.")
#endif

#if CONFIG_SPIRAM_ALLOW_BSS_SEG_EXTERNAL_MEMORY
// Forces bss variable into external memory. "
#define EXT_RAM_BSS_ATTR _SECTION_ATTR_IMPL(".ext_ram.bss", __COUNTER__)
// Forces data into external memory BSS and maps it to coredump
#define COREDUMP_EXTRAM_ATTR _SECTION_ATTR_IMPL(".ext_ram.coredump", __COUNTER__)
#else
#define EXT_RAM_BSS_ATTR
#define COREDUMP_EXTRAM_ATTR
#endif

// Forces data into noinit section to avoid initialization after restart.
#define __NOINIT_ATTR _SECTION_ATTR_IMPL(".noinit", __COUNTER__)

#if CONFIG_SPIRAM_ALLOW_NOINIT_SEG_EXTERNAL_MEMORY
// Forces data into external memory noinit section to avoid initialization after restart.
#define EXT_RAM_NOINIT_ATTR _SECTION_ATTR_IMPL(".ext_ram_noinit", __COUNTER__)
// Forces data into external memory noinit section and maps it to coredump
#define COREDUMP_EXTRAM_NOINIT_ATTR _SECTION_ATTR_IMPL(".ext_ram_noinit.coredump", __COUNTER__)
#else
// Place in internal noinit section
#define EXT_RAM_NOINIT_ATTR __NOINIT_ATTR
#define COREDUMP_EXTRAM_NOINIT_ATTR
#endif

// Forces code into DRAM instead of flash and map it to coredump
// Use dram2 instead of dram1 to make sure this section will not be included
// by dram1 section in the linker script
#define COREDUMP_DRAM_ATTR _SECTION_ATTR_IMPL(".dram2.coredump", __COUNTER__)

// Forces to not inline function
#define NOINLINE_ATTR __attribute__((noinline))

#if !defined(__clang__) && __GNUC__ >= 15
// Marks a character array as not null-terminated to avoid string-related optimizations or warnings
#define NONSTRING_ATTR __attribute__ ((nonstring))
#else
#define NONSTRING_ATTR
#endif

// This allows using enum as flags in C++
// Format: FLAG_ATTR(flag_enum_t).
// Please use out of the extern "C"{} block of the header, otherwise there will be definition conflicts.
#ifdef __cplusplus

// Inline is required here to avoid multiple definition error in linker
#define FLAG_ATTR_IMPL(TYPE, INT_TYPE) \
FORCE_INLINE_ATTR constexpr TYPE operator~ (TYPE a) { return (TYPE)~(INT_TYPE)a; } \
FORCE_INLINE_ATTR constexpr TYPE operator| (TYPE a, TYPE b) { return (TYPE)((INT_TYPE)a | (INT_TYPE)b); } \
FORCE_INLINE_ATTR constexpr TYPE operator& (TYPE a, TYPE b) { return (TYPE)((INT_TYPE)a & (INT_TYPE)b); } \
FORCE_INLINE_ATTR constexpr TYPE operator^ (TYPE a, TYPE b) { return (TYPE)((INT_TYPE)a ^ (INT_TYPE)b); } \
FORCE_INLINE_ATTR constexpr TYPE operator>> (TYPE a, int b) { return (TYPE)((INT_TYPE)a >> b); } \
FORCE_INLINE_ATTR constexpr TYPE operator<< (TYPE a, int b) { return (TYPE)((INT_TYPE)a << b); } \
FORCE_INLINE_ATTR TYPE& operator|=(TYPE& a, TYPE b) { a = a | b; return a; } \
FORCE_INLINE_ATTR TYPE& operator&=(TYPE& a, TYPE b) { a = a & b; return a; } \
FORCE_INLINE_ATTR TYPE& operator^=(TYPE& a, TYPE b) { a = a ^ b; return a; } \
FORCE_INLINE_ATTR TYPE& operator>>=(TYPE& a, int b) { a = a >> b; return a; } \
FORCE_INLINE_ATTR TYPE& operator<<=(TYPE& a, int b) { a = a << b; return a; }

#define FLAG_ATTR_U32(TYPE) FLAG_ATTR_IMPL(TYPE, uint32_t)
#define FLAG_ATTR FLAG_ATTR_U32

#else
#define FLAG_ATTR(TYPE)
#endif

// Implementation for a unique custom section
//
// This prevents gcc producing "x causes a section type conflict with y"
// errors if two variables in the same source file have different linkage (maybe const & non-const) but are placed in the same custom section
//
// Using unique sections also means --gc-sections can remove unused
// data with a custom section type set
#define _COUNTER_STRINGIFY(COUNTER) #COUNTER

#ifndef CONFIG_IDF_TARGET_LINUX
#define _SECTION_ATTR_IMPL(SECTION, COUNTER) __attribute__((section(SECTION "." _COUNTER_STRINGIFY(COUNTER))))
#define _SECTION_FORCE_ATTR_IMPL(SECTION, COUNTER) __attribute__((noinline, section(SECTION "." _COUNTER_STRINGIFY(COUNTER))))
#else
// Custom section attributes are generally not used in the port files for Linux target, but may be found
// in the common header files. Don't declare custom sections in that case.
#define _SECTION_ATTR_IMPL(SECTION, COUNTER)
#define _SECTION_FORCE_ATTR_IMPL(SECTION, COUNTER)
#endif

/*
 * Portable link-time section macros.
 *
 * Unlike _SECTION_ATTR_IMPL (which is a no-op on Linux), these macros emit
 * real section attributes on every platform: embedded ELF, Linux ELF, and
 * macOS Mach-O.  Use them when data MUST be placed in a custom section
 * regardless of the target (e.g. error-code tables, init-function arrays).
 *
 * PLACE_IN_SECTION("name")
 *   Place a variable into section "name" with used + aligned(4).
 *   Section name is given WITHOUT a leading dot; the macro adds the
 *   appropriate prefix ("." for ELF, "__DATA," for Mach-O).
 *
 * _SECTION_ATTR_IMPL_GENERIC("name", counter)
 *   Like PLACE_IN_SECTION but appends a unique counter suffix so that
 *   multiple definitions in the same translation unit get unique sub-sections
 *   (enables SORT in the linker).
 *
 * _SECTION_ATTR_SYMBOL_DECL_GENERIC(TYPE, section_name)
 *   Declare the start/end boundary symbols for iterating over all entries
 *   placed in a section.  On ELF these are plain extern symbols provided
 *   by the linker script; on macOS a constructor resolves them at runtime
 *   via getsectiondata().
 *
 * _SECTION_START(section_name) / _SECTION_END(section_name)
 *   Evaluate to a (const TYPE *) pointing to the first / past-the-last
 *   entry — works uniformly across platforms.
 */
#if defined(__APPLE__) && defined(__MACH__)
/* ---------- macOS (Mach-O) ---------- */
#include <mach-o/getsect.h>
#include <mach-o/ldsyms.h>
#include <mach-o/dyld.h>

#define _SECTION_ATTR_IMPL_GENERIC(SECTION, COUNTER) \
    __attribute__((used, section("__DATA," SECTION)))

#define PLACE_IN_SECTION(SECTION) _SECTION_ATTR_IMPL_GENERIC(SECTION, __COUNTER__)

#define _SECTION_ATTR_SYMBOL_DECL_GENERIC(TYPE, SECTION_NAME) \
    static const TYPE *_##SECTION_NAME##_start_ptr; \
    static const TYPE *_##SECTION_NAME##_end_ptr; \
    __attribute__((constructor)) \
    static void _init_section_##SECTION_NAME(void) { \
        unsigned long size = 0; \
        const TYPE *s = (const TYPE *)getsectiondata( \
            &_mh_execute_header, "__DATA", #SECTION_NAME, &size); \
        if (s && size > 0) { \
            _##SECTION_NAME##_start_ptr = s; \
            _##SECTION_NAME##_end_ptr = s + (size / sizeof(TYPE)); \
        } else { \
            _##SECTION_NAME##_start_ptr = (const TYPE *)0; \
            _##SECTION_NAME##_end_ptr = (const TYPE *)0; \
        } \
    }

#define _SECTION_START(SECTION_NAME)  (_##SECTION_NAME##_start_ptr)
#define _SECTION_END(SECTION_NAME)    (_##SECTION_NAME##_end_ptr)

#else /* ELF targets (Linux and embedded) */

/* Use the variable's own natural alignment so that pointer arithmetic over
 * the section (end - start) gives the correct entry count with no padding gaps.
 * On 32-bit embedded targets uint32_t aligns to 4; on 64-bit hosts a struct
 * with a pointer member aligns to 8 — both correct without an explicit override. */
#define _SECTION_ATTR_IMPL_GENERIC(SECTION, COUNTER) \
    __attribute__((used, section("." SECTION "." _COUNTER_STRINGIFY(COUNTER))))

#define PLACE_IN_SECTION(SECTION) _SECTION_ATTR_IMPL_GENERIC(SECTION, __COUNTER__)

#define _SECTION_ATTR_SYMBOL_DECL_GENERIC(TYPE, SECTION_NAME) \
    extern TYPE _##SECTION_NAME##_start; \
    extern TYPE _##SECTION_NAME##_end;

#define _SECTION_START(SECTION_NAME)  (&_##SECTION_NAME##_start)
#define _SECTION_END(SECTION_NAME)    (&_##SECTION_NAME##_end)

#endif /* platform selection */

/* Use IDF_DEPRECATED attribute to mark anything deprecated from use in
   ESP-IDF's own source code, but not deprecated for external users.
*/
#ifdef CONFIG_IDF_CI_BUILD
#define IDF_DEPRECATED(REASON) __attribute__((deprecated(REASON)))
#else
#define IDF_DEPRECATED(REASON)
#endif

#ifdef __cplusplus
}
#endif
#endif /* __ESP_ATTR_H__ */