ECE222 Lecture Notes - Lecture 3: Clock Signal, Baud, Subroutine
8 Dec 2017
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Cpsr - current program status register which the condition flags. A push operation moves a new operand to the top-of-stack. Pop operation takes the top of stack and moves the next lower element to the top. Arm uses a branch and link (bl) instruction for subroutine calls. In arm, the stack is realized in memory with the aid of r13, called stack pointer. Stack can grow to either smaller or larger memory addresses, usually lower to prevent collision. Stack pointer always pointing to the top of stack. Decrement by appropriate amount, update stack pointer. Translation of a program written in assembly language to a program is performed by an assembler. In assembly languages, one statement = one instruction (with a couple of exceptions) Dcd labels and initializes the value of operands. Sum dcd 0 associates sum with a memory location and sets that locations value to zero. Ten equ 10 associates the value 10 with the label ten.
