Addressing modes for Load and Store

Addressing modes for Load and Store - Addressing modes for...

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Addressing modes for Load and Store See also Textbook section 5.4, slides 38-43 in “ARM Instruction Set” pdf and “The ARM Assembly Language – A Short Introduction” section 4.5. Lets Start with the simplest modes and give good reasons for how they work and why they are useful. Also note that I am not talking about using the barrelshifter, nor BYTE/HALFWORD access. First a definition: Effective Address (EA) – The final address used to access the data in memory. On the ARM addresses are always based on an address in a register (base register) from which the EA is computed. The different addressing modes are useful to easily access data structures such as arrays and structs. Simplest situation: EA (Address) is in a register Ex: LDR R1, [R0] @ R0 = 0x1040 Register R0 contains the EA. R1 is loaded (with value 23) from address pointed to by R0, in this case 0x1040. Previous instructions had to put this address into R0.
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Pre-Indexed - A constant or a register is added to base register to calculate the EA
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This note was uploaded on 12/20/2010 for the course CSC CSCC85 taught by Professor Lorincz during the Spring '10 term at University of Toronto- Toronto.

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Addressing modes for Load and Store - Addressing modes for...

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