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Diffstat (limited to 'include/asm.s')
| -rw-r--r-- | include/asm.s | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/include/asm.s b/include/asm.s new file mode 100644 index 0000000..67b195c --- /dev/null +++ b/include/asm.s @@ -0,0 +1,22 @@ +;; Jump And Link: jump to subroutine but use the return address that the caller +;; had whenever the given subroutine runs `rts`. In other words, "link" the +;; return address from the caller to the callee. +;; +;; This is in practice the same as using `jmp` but it bears the semantic +;; connotation of the `jsr` one. That is, instead of this: +;; +;; jsr subroutine +;; rts +;; +;; It's more adviseable to do the following for better stack management: +;; +;; jmp subroutine +;; +;; That being said, the `jmp` instruction is also used in many other contexts, +;; and so sometimes it's needed to clarify that: "no, I have not messed up, +;; using `jmp` here instead of `jsr` is deliberate". Hence, instead of adding a +;; comment every time this small optimization is being done, use this +;; pseudo-instruction. +.macro JAL ADDR + jmp ADDR +.endmacro |