How to Link Two Project Files Using Softune Workbench

Transcription

1 How to Link Two Project Files Using Softune Workbench

2 Introduction 1 General description of various projects 1 Adding two Projects together 1 CASE I Linking project as a library file (lib) 2 CASE II Linking project with a relative format load module (REL) 4 CASE III Linking project with an Object module (obj) 4 Conclusion 5 Fujitsu Microelectronics America, Inc i

3 How to Link Two Project Files Using Softune Workbench Introduction A program is often divided into several modules Each module can be compiled and assembled independently from other module The purpose of this modular development is to reduce the development time and cost Sometimes user may want to add third party drivers, or a project developed elsewhere, is required to combine with the original project This article discusses how to combine two projects without changing original source code General description of various projects The softune workbench, a software development environment for Fujitsu Microcontrollers provides four different ways to create the project files These project types are Absolute project, Library project, Relocatable project and REALOS absolute project These projects files are designed based on the user application requirements The main difference between the projects is the way linker links the projects In the absolute projects, an absolute section exists The address to the sections is allocated in such a way that allocation addresses do not overlap The main area is specified by the -ra or -ro option in linker setting of the project file If there are additional sections defined in the project file without an absolute address, then the ROM area or RAM area is determined based on the section attributes And these sections are allocated to free space of each area by linker automatically If there is any relocatable section or project file (rel) in the project file, in this case that those sections or projects are allocated in descending order of the alignment value and size starting with the section of the largest alignment value and size In this way, optimal allocation is implemented In case of relocatable project, a load module of relative format created without performing address resolution A file of this format can be reentered in the linker or can be combined with absolute project The relocatable load module cannot be debugged using the simulator or emulatoer debugger Library project is same as relocatable project module No address resolution in the project unless user defines in C or in Assembly file by pragma statement If any reference symbol is unresolved in other object module, then the linker searches the library file specified at that time The library load module cannot be debugged using the simulator or emulatoer debugger REALOS project type is used only when you are using the real time operating system, REALOS from Fujitsu Adding two Projects together The two projects are combined at linking stage The linker is a linkage tool that reads object module output from C compiler and assembler or relocatable module generated by linker, and generates absolute format object file or relocatable load module file (lib or rel) Figure below shows the relationship: Object Module Figure 1 Linker Relocatable Load Module Absolute Load Module If you want to combine the multiple object modules or relocatable modules (rel, lib), it will be done at the linking stage Figure 2 shows the relationship between a linker and input-output files (Please refer to SOFTUNE LINKAGE KIT MANUAL for more information)

4 How to Link Two Project Files Using Softune Workbench Figure 2 Relationship between a linker and input-output files Assembler Library Relative format object Assemble list (lib) (obj) (lst) Relative format load module (rel) Linker Absolute format load module (abs) Absolute format assemble list object contents list (mp1) (mpx) (mps) (mpm) The user, who has the requirement to combine the multiple project, the best method, is to make one project as an absolute module and create all other projects as a relocatable project or Library project The load module of library project (lib) or the relocatable project (rel) then combined to the absolute project at linking stage These methods are discussed in detail as follows: CASE I Linking project as a library file (lib) A good example of this case is where the user wants to combine a device or protocol driver like CAN driver into their program This driver can be built as a library file Here are some important considerations when creating the library project: If you combine the library module with other modules (abs or rel or obj), linker first acquires information from rel and obj module, and if the information is insufficient then only the library file is retrieved So only necessary modules of library project is linked It is not possible to assign the absolute address in library project by linker option However address can be defined in assembly or C-code as follows In C code: #pragma section CODE=program, attr=code, locate=0xff In assembly: SECTION program, CODE, LOCATE=H FF:H 200 So while creating the library project, if it is required particular section to locate in the specify address, for example program in above example should be located at address 0xFF, care has to be taken to define the absolute address using the pragma or section statement Linker identifies a section by the section name So do not define sections with the same section name in library project and in absolute project, even with different types of contents and attributes For sections containing the ABS attribute, if they are overlapped, a warning message will show up after linking This won t affect the program execution The user should understand the searching sequence and priority when linking with a library file An example is shown in Figure 3 2 Fujitsu Microelectronics America, Inc

5 Figure 3 An example of a search when there is one library file Application Note Object X Object X Reference (S1) Reference (S2) Object Y Object Y Definition {S2} Load Module after linking X Reference (S1) Reference (S2) Y Definition {S2} A Definition {S1} Library file (lib) Symbol table {S1} A {S2} B Module A Definition {S1} Extracted module A Definition {S1} Module B Definition {S2} In the Figure 3, as a result of combining object modules X and Y and library module (lib), the external reference symbol (S2) referenced in Object module X is solved by the external defined symbol {S2} in Object module Y But the external reference symbol (S1) used in Object module X is unresolved Now linker will search the libraries and it founds that module A of library module contains the definition of symbol {S1} So it will link the project successfully But in the above example there is a duplicate definition of symbol {S2} One definition is defined in Object module Y and another one is defined in the library module But linker will use the definition {S2} from object Y instead of module B in library file So please don t use the same definition symbol in object and library module, especially if they have different functions Understanding searching sequence for linking objects and library file will prevent unnecessary modules from being extracted from library file and linked to the wrong module into the final load module While creating library project, make sure to enable the output list option in librarian This option generates output file mp2 In this file you can confirm the sections defined in the library project However the sections are listed by name only For example if you define the code section as follows in the library project: Fujitsu Microelectronics, America Inc 3

6 How to Link Two Project Files Using Softune Workbench #pragma section CODE=program, attr=code, locate=0xff0000 void FlashLEDs(void) { unsigned long cnt; DDR4 = 0xFF; /* set parallel port direction register : output */ PDR4 = 0xFF; /* switch off all leds */ while(1) { for(cnt = 0; cnt < 30000; cnt++); /* wait */ PDR4--; /* counter */ } } In this case, the output file of librarian project will show only section name program and entry will be something like this: [ Module Name ] [ Entry Date ] [ Creation Date ] program a date and time another date and time- - Section Type Size -- program CODE 0x D But if you combine this library project with absolute project, the linker output-mapping file (mp1) will show the entry as follows: S_Addr - E_Addr Size Section Type Al Section 00FF FF003D 00003D CODE N R-XI 00 ABS program So this confirms that your sections are the way you want in the memory CASE II Linking project with a relative format load module (REL) The procedure for linking relocatable module with absolute project is same as linking the library project as mentioned above Except, linker links all the modules, whether it is used or not used in the system However, there are still several situations that should be avoided: Do not use the same symbol definition in both projects, such as _start and _main Do not define the same module name in both projects, even if they have different functions CASE III Linking project with an Object module (obj) In this method a project file is combined with one or multiple object module of C or asm files This method is useful when the software is divided in various modules among the team members The object module is combined at the linking stage If it is necessary to have the object module located at specific address in the memory, it is better to define a section in the C or asm file itself After building the projects file, confirm the lst file for the section allocation in the memory 4 Fujitsu Microelectronics America, Inc

7 Application Note General steps for combining the absolute and library or relocatable project Create the absolute project by selecting project type as ABS in softune workbench Create all the other projects as library or relocatable project Build the library or relocatable project This will create the rel or lib module This module you can find in the abs directory of the project Add the rel, obj or lib module to the absolute project This can be done using Project>add member Now build the project again The two project files are combined now Check the linker output (mp1) to get the more information about mapping of the project Conclusion This article describes how to link two projects The goal is to limit modifications in the source code However in some cases, a user has to change the duplicated external symbol definition and module name But these changes are minimal So, looking at the overall procedure, the modular scheme is easy and save time in the development Fujitsu Microelectronics, America Inc 5

8 FUJITSU MICROELECTRONICS AMERICA, INC Corporate Headquarters 1250 East Arques Avenue, M/S 333, Sunnyvale, CA Tel: (800) Fax: (408) Internet: Fujitsu Microelectronics America, Inc All rights reserved All company and product names are trademarks or registered trademarks of their respective owners MCU-AN /2003