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dev:crosscompiler:backend:linker32

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dev:crosscompiler:backend:linker32 [2018/01/04 15:31] – created ursgrafdev:crosscompiler:backend:linker32 [2022/12/20 10:00] (current) – ursgraf
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 When the system ist starting up, the [[dev:rts:start|Runtime System]] reads the start addresses of the constant block for all classes from the //System Table// (see below). With the predefined offset //cblkClinitAddrOffset// the address of the class constructor can be fetched in order to load a class. With another offset the heap manager can read the global references of this class. This information is used by the garbage collection. //codeBase// holds the start address of code of a class whereas //codeSize// is the size of the code. Methods, which are defined in the configuration as system methods and which are assigned a fixed offset are excluded from //codeSize// (Exception Handlers). When the system ist starting up, the [[dev:rts:start|Runtime System]] reads the start addresses of the constant block for all classes from the //System Table// (see below). With the predefined offset //cblkClinitAddrOffset// the address of the class constructor can be fetched in order to load a class. With another offset the heap manager can read the global references of this class. This information is used by the garbage collection. //codeBase// holds the start address of code of a class whereas //codeSize// is the size of the code. Methods, which are defined in the configuration as system methods and which are assigned a fixed offset are excluded from //codeSize// (Exception Handlers).
  
-In the compiler the constant block is modeled as linked list of ''ch.ntb.inf.deep.linker.ConstBlkEntry''. Depending on the type of entry one of the following classes is used.+In the compiler the constant block is modeled as linked list of ''org.deepjava.linker.ConstBlkEntry''. Depending on the type of entry one of the following classes is used.
   * **''AddressEntry''**: For entries representing an address.   * **''AddressEntry''**: For entries representing an address.
   * **''ConstantEntry''**: For entries representing a constant (StdConstant).   * **''ConstantEntry''**: For entries representing a constant (StdConstant).
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 ===== Calculate Size and Offsets ===== ===== Calculate Size and Offsets =====
 [{{  dev:crosscompiler:linker_code_methods.png?350px&direct|Machine Code: Size and Offsets}}] [{{  dev:crosscompiler:linker_code_methods.png?350px&direct|Machine Code: Size and Offsets}}]
-Before the memory map can be fixed, a couple sizes and offsets must be calculated for each class: +Before the memory map can be fixed, a couple of sizes and offsets must be calculated for each class: 
-  * ''void calculateCodeSizeAndOffsets(Class)'': This methods determines the size of the machine code of the whole class and sets the field //offset// of each method of this class. //offset// is the byte offset of the machine code of a method in the memory starting from the start address of the code of this class. If a method offset is given by the configuration (e.g. exception handlers), then this method is not included in the culculation of the code size. The offset given by the configuration is not relative to the base of a class but to the base of the appropriate segment.+  * ''void calculateCodeSizeAndOffsets(Class)'': This methods determines the size of the machine code of the whole class and sets the field //offset// of each method of this class. //offset// is the byte offset of the machine code of a method in the memory relative to the start address of the code of this class. If a method offset is given by the configuration (e.g. exception handlers), then this method is not included in the calculation of the code size. The offset given by the configuration is not relative to the base of a class but to the base of the appropriate segment.
   * ''void calculateGlobalConstantTableSize()'': This method calculates the size of the global constant table.   * ''void calculateGlobalConstantTableSize()'': This method calculates the size of the global constant table.
  
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   - The system runs from the flash   - The system runs from the flash
   - The system runs from the RAM.   - The system runs from the RAM.
-  - The base system is in the flash. Further classes are later loaded into the RAM. This case needs two system tables. The flash holds a system table which contains only classes which are present in the flash. The system table in the RAM must hold all classes. IMPORTANT This feature is not implemented yet IMPORTANT+  - The base system is in the flash. Further classes are later loaded into the RAM. This case needs two system tables. The flash holds a system table which contains only classes which are present in the flash. The system table in the RAM must hold all classes. <wrap hi>This feature is not implemented yet</wrap>
  
 In the compiler the system table is modeled as list. as elements it uses the same blocks as for the constant block. Additionally ''SysTabEntry'' is used to reference the constant block of a class. In the compiler the system table is modeled as list. as elements it uses the same blocks as for the constant block. Additionally ''SysTabEntry'' is used to reference the constant block of a class.
dev/crosscompiler/backend/linker32.1515076278.txt.gz · Last modified: 2018/01/04 15:31 by ursgraf

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