esp-idf/components/esp32/include/esp_attr.h

// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at

//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef __ESP_ATTR_H__
#define __ESP_ATTR_H__

#include "sdkconfig.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.

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

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

// 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

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

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

#if CONFIG_SPIRAM_ALLOW_BSS_SEG_EXTERNAL_MEMORY
// Forces bss variable into external memory. "
#define EXT_RAM_ATTR _SECTION_ATTR_IMPL(".ext_ram.bss", __COUNTER__)
#else
#define EXT_RAM_ATTR 
#endif

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

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

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

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

// Forces data into RTC slow 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 to not inline function
#define NOINLINE_ATTR __attribute__((noinline))

// 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 _SECTION_ATTR_IMPL(SECTION, COUNTER) __attribute__((section(SECTION "." _COUNTER_STRINGIFY(COUNTER))))

#define _COUNTER_STRINGIFY(COUNTER) #COUNTER

#endif /* __ESP_ATTR_H__ */