Imagecraft c compiler and development environment for the atmel avr

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ICCV8 for AVR – C Compiler for Atmel AVRint junk;#pragma data:dataEEPROM Memory eeprom - this area contains the EEPROM data. EEPROM data is written to.eep as an Intel HEX file regardless of the output file format.The job of the linker is to collect areas of the same types from all the input object filesand concatenate them together in the output file. See Linker Operations.User Defined Memory RegionsIn most cases, you do not need to specify the exact location of a particular data item.For example, if you have a global variable, it will be allocated somewhere in the dataarea, and you do not need to specify its location.However, there are occasions where you want to specify the exact location for a dataitem or a group of data: battery-backed SRAM, dual-port SRAM, etc. - sometimes it is necessary toallocate some items in special RAM regions.There are two ways to handle this.1. relocatable area - in an assembly module, you can create a new program areaand then you can specify its starting address under the “Other Options” edit box inBuild Options - Target. For example, in an assembly file:.area battery_sram_var1:: .blkw 1 ; note _ in the front_var2:: .blkb 1 ; and two colonsIn C, these variables can be declared as:extern int var1;extern char var2;Let’s say the battery-backed SRAM starts at 0x4000. In the Advanced=>OtherOptions edit box, you write:-bbattery_sram:0x4000Please refer to the page Build Options - Target for full description of addressspecifier.2. absolute area - you can also define program areas that have absolute startingaddresses, eliminating the need to specify the address to the linker. For example,150
ICCV8 for AVR – C Compiler for Atmel AVRusing the same example as before, you can write the following in an assembly file:.area battery_sram(abs).org 0x4000_var1:: .blkw 1 ; note _ in the front_var2:: .blkb 1 ; and two colonsThe (abs) attribute tells the assembler that the area does not need relocationand it is valid to use the .org directive in the area. In this example, we use .orgto set the starting address. In C the declaration will be exactly the same as before.If you have data that have initialized values, then you can also use the followingpragma in C to define them (note this only works with data that have initializedvalues):#pragma abs_address:0x4000int var1 = 5;char var2 = 0;#pragma end_abs_address151
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