Intro to Assembly Language: Lecture Notes

Here are the General-Purpose CPU registers that we'll work with and their descriptions:

Register	Size	Typical Purpose (Convention)
`rax` = `r0`	64-bit	Accumulator; return value; syscall number
`rbx` = `r1`	64-bit	General-purpose
`rcx` = `r2`	64-bit	Counter (loops, shifts)
`rdx` = `r3`	64-bit	Data register; I/O length; syscall arguments
`rsi` = `r4`	64-bit	Source index; pointer to input data
`rdi` = `r5`	64-bit	Destination index; pointer to output data
`rbp` = `r6`	64-bit	Base pointer (stack frame reference)
`rsp` = `r7`	64-bit	Stack pointer (top of stack)
`r8`	64-bit	General-purpose; syscall arguments
`r9` to `r15`	64-bit	General-purpose