diff options
| -rw-r--r-- | .nasm/segments.txt | 2 | ||||
| -rw-r--r-- | src/enemies.s | 13 |
2 files changed, 14 insertions, 1 deletions
diff --git a/.nasm/segments.txt b/.nasm/segments.txt index 2367e2f..f89b010 100644 --- a/.nasm/segments.txt +++ b/.nasm/segments.txt @@ -1,4 +1,4 @@ - HEADER: 16/16 (100%) -- ROM0: 6448/32762 (19.68%) +- ROM0: 6452/32762 (19.69%) - ROMV: 6/6 (100%) - ROM2: 8192/8192 (100%) diff --git a/src/enemies.s b/src/enemies.s index facb255..7097af5 100644 --- a/src/enemies.s +++ b/src/enemies.s @@ -613,7 +613,16 @@ .endproc ;; The enemy has been set to dust, remove it. + ;; + ;; NOTE: the 'x' register is modified, the 'y' register is _preserved_. .proc bite_the_dust + ;; This function might be called by loops which abuse index + ;; registers. Luckily that's not the case for the 'x' register, but at + ;; least the loop on Bullets::update() does heavy use of the 'y' + ;; register. Preserve it now on the stack. + tya + pha + ;; Invalidate this enemy. lda #$FF ldx Enemies::zp_pool_index @@ -634,6 +643,10 @@ ldx Enemies::zp_pool_index sta Enemies::zp_enemies_pool_base + 3, x + ;; Restore back the value for the 'y' register. + pla + tay + rts .endproc |