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For example, if the subroutine modifies a 64-bit global variable on a 32-bit machine, the operation may be split into two 32-bit operations, and thus, if the subroutine is interrupted while executing, and called again from the interrupt handler, the global variable may be in a state where only 32 bits have been updated.
Some architectures have two link registers: a standard "branch link register" for most subroutine calls, and a special "interrupt link register" for interrupts. One of these is ARCv2 ( ARC processors using version 2 of the ARCompact architecture), which uses general-purpose-registers r29 for the interrupt link register and r31 for the branch ...
Ralf Brown's Interrupt List (aka RBIL, x86 Interrupt List, MS-DOS Interrupt List or INTER) is a comprehensive list of interrupts, calls, hooks, interfaces, data structures, CMOS settings, memory and port addresses, as well as processor opcodes for x86 machines from the 1981 IBM PC up to 2000 (including many clones), [1] [2] [nb 1] most of it still applying to IBM PC compatibles today.
"Instrumenting" all the source code with additional source statements that issue a function that invokes an internal or external debug subroutine, is yet another common approach. This method increases the binary size and might adversely affect normal memory allocation and exception handlers .
For example, hardware timers send interrupts to the CPU at regular intervals. Most operating systems execute a HLT instruction when there is no immediate work to be done, putting the processor into an idle state. In Windows NT, for example, this instruction is run in the "System Idle Process". On x86 processors, the opcode of HLT is 0xF4.
In embedded systems, trampolines are short snippets of code that start up other snippets of code. For example, rather than write interrupt handlers entirely in assembly language, another option is to write interrupt handlers mostly in C, and use a short trampoline to convert the assembly-language interrupt calling convention into the C calling ...
A label is an explicit name or number assigned to a fixed position within the source code, and which may be referenced by control flow statements appearing elsewhere in the source code. A label marks a position within source code and has no other effect. Line numbers are an alternative to a named label used in some languages (such as BASIC ...
In computer systems programming, an interrupt handler, also known as an interrupt service routine or ISR, is a special block of code associated with a specific interrupt condition. Interrupt handlers are initiated by hardware interrupts, software interrupt instructions, or software exceptions , and are used for implementing device drivers or ...