From 88c91a8eecfc118f57f1946d364e44b3d903e596 Mon Sep 17 00:00:00 2001 From: Michal Isalski Date: Mon, 31 Aug 2026 15:30:11 +0200 Subject: [PATCH] Reduced operations to get -1 in register --- array.asm | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/array.asm b/array.asm index bfcb3ed..3d06c91 100644 --- a/array.asm +++ b/array.asm @@ -11,7 +11,7 @@ pub find_index: push r12 ; We will store the predicate pointer here push r11 ; We will store the current pointer here push r10 ; We will store the stride here - push r9 ; We will store the bytes left here + push r9 ; We will store the final address here push r8 ; We will store the mask here push r1 ; We need the array pointer to calculate the item index @@ -19,14 +19,14 @@ pub find_index: mov r11, r1 mov r10, r3 mov r9, r2 - lsl r9, r9, r3 + lsl r9, r9, r3 ; We calculate bytes left + add r9, r9, r1 ; We add the start address to get the final address push r13 ; We save up the return address because we will provide our own to the predicate counter r13 add r13, r13, 52 ; Point to just after the predicate call - we can set this up now so we don't waste loop cycles - mov r8, 0 - not r8, r8 ; We create a mask of 0xFFFFFFFF + nand r8, zr, zr ; We create a mask of 0xFFFFFFFF mov r6, 4 sub r6, r6, r3 ; We create a "negative stride", e.g. 4 -> 0, 2 -> 2, 1 -> 3 lsl r6, r6, 3 @@ -45,16 +45,14 @@ pub find_index: jneq find_index_found_item ; If we found the item, we jump out ; If we didn't, move to next item add r11, r11, r10 ; We add the stride to the pointer - sub r9, r9, r10 ; We decrease bytes left - cmp r9, zr + cmp r11, r9 ; We compare with the final address jeq find_index_not_found ; If we reached the end we're done jmp find_index_loop find_index_not_found: add sp, sp, 4 ; The predicate context is not useful pop r13 ; We get our return address - mov r1, 0 - not r1, r1 ; We put -1 in r1 + nand r1, zr, zr ; We put -1 in r1 add sp, sp, 4 ; The old array pointer are not useful jmp find_index_postamble