#Iar arm code alignment plus

вЂbssвЂ™ is for the uninitialized data in RAM which is initialized with zero in the startup code. The linker allocates the data in FLASH which then is copied from ROM to RAM in the startup code. вЂdataвЂ™ is for initialized variables, and it counts for RAM and FLASH.

#Iar arm code alignment plus

вЂtextвЂ™ is my code, vector table plus constants. map file in mind), things get much clearer: The way how the initialized data is reported might be confusing.

I hope I have sorted out things in a correct way. romp 0x1ffff030 0x18 load address 0x00001b60ДЄh! That actually is not in RAM, but in FLASH: the linker maps this to the FLASH address 0x1b60! So this size 0x18 really needs to be added to the FLASH size too! Summary But it looks confusing: it is shown with addresses in RAM? Checking the linker map file shows. romp is used by the linker for the вЂcopy-downвЂ™ and initialization of. data is for my initialized вЂtableвЂ™ variable in RAM (5*4 bytes=0x14) That makes the total of 0x1c+0x800=0x81c shown in вЂBerkeleyвЂ™ format. user_heap_stack: this is the heap defined in the ANSI library for malloc() calls. bss is my uninitialized (zero-outed) variable area. That makes the 0xc0+0x134c=0x140c for text in вЂBerkeleyвЂ™. text is my code plus constants, and is in FLASH memory. interrupts is my interrupt vector table, and. debug_frame are not ending up in the target, they are debug and other information. IвЂ™m using an ARM Cortex-M0+ in my example, so addresses greater 0x1ffff000 are in RAM. I get this in вЂSystem VвЂ™ mode: section size addr While in вЂBerkeleyвЂ™ mode I get: text data bss dec hex filename

It produces similar information as shown above, but with greater detail. GNU Print Size Option in CodeWarrior for MCU10.3 The вЂSystem VвЂ™ option can be set directly in the Eclipse panel: The size (or printsize) GNU utility has more options: size The вЂdecвЂ™ (as a decimal number) is the sum of text, data and bss: dec = text + data + bss Size вЂ“ GNU Utility Memset(_START_BSS, 0, (_END_BSS - _START_BSS)) The bss segment is initialized in the startup code by the zero_fill_bss() function: As bss ends up in RAM, and RAM is very valuable for a microcontroller, I want to keep the amount of variables which end up in the. рџ’Ў I like to remember вЂbssвЂ™ as вЂBetter Save SpaceвЂ™ :-). This is best explained with following (global/extern) variable:ДЄdding this variable will increase the вЂbssвЂ™ portion by 4: text data bss bss, or BSS) is the abbreviation for вЂBlock Started by SymbolвЂ™ by an old assembler (see this link). The вЂbssвЂ™ contains all the uninitalized data. вќ— The вЂdataвЂ™ only has the initialization data (in my example 0x12345678. That amount of data in FLASH is *not* counted in the text portion. So I need to count the вЂdataвЂ™ size twice: that size will end up in RAM, plus will occupy FLASH/ROM. Just one thing to consider: my variable вЂmyVarвЂ™ will use space in RAM (4 bytes in my case), *plus* space in FLASH/ROM for the initialization value (0x12345678). For the startup code used by CodeWarrior for MCU10.3 for Kinetis-L (ARM Cortex-M0+), this is performed in _copy_rom_sections_to_ram(): The code will assign/copy the initialization value. The initialization of the variable is done during the normal ANSI startup code. But the initialization (0x12345678) *is* constant, and can live in FLASH memory. This variable вЂmyVarвЂ™ is not constant, so it will end up in RAM. This is best explained with the following (global/extern) variable:ДЄdding above variable to my application will increase the вЂdataвЂ™ portion by 4 bytes: text data bss In summary: вЂtextвЂ™ is what ends up typically in FLASH and has code and constant data. That variable вЂtableвЂ™ will be in FLASH, initialized with the values specified in the source.ДЄnother thing which is included in вЂtextвЂ™ is the interrupt vector table (more on this later). Sources/main_c.oД«ut it does not only contain functions, it has constant data as too. text segment, as I can see in the map file generated by the linker: *(.text*) Likewise, my new function вЂfooвЂ™ gets added to the. To my program, the вЂtextвЂ™ part increases so: text data bss * dummy function to show how this adds to 'text' */ Note: IвЂ™m using the ARM GNU вЂprintsizeвЂ™ utility for gcc, with an example for Kinetis-L (KL25Z). I have been asked by a reader of this blog what these item numbers really mean. In вЂњ Code Size Information with gcc for ARM/KinetisвЂќ I use an option in the ARM gcc tool chain for Eclipse to show me the code size: text data bss dec hex filename