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+====== Alignment calculation in three instructions ======
+Found [[https://hg.pushbx.org/ecm/warplink/rev/319bf908e2e5#l2.101|in a 2025-08-29 changeset]] of the ecm fork of WarpLink:
+<code>    mov bx, [alignment_table + bx]	; bx = alignment mask
+	and ax, bx
+	neg ax
+	and ax, bx</code>
+''and'' ''neg'' ''and''. That's odd. I assume it works because I would have worked it out at the time but it's not intuitive.
+===== =====
+The first ''and'' is obvious enough: Calculate how far past the aligned boundary we are. Zero means exactly aligned, 1 means 1 byte past alignment, etc.
+Then ''neg'': Negative value of how far past the aligned boundary. Zero if exactly aligned.
+Then the second ''and'': -1 (0FFFFh) results in ''ax'' = alignment mask. -2 (0FFFEh) results in ''mask clr 1'' (one below the mask). -3 (0FFFDh) results in ''mask clr 2'' (two below the mask).
+{{tag>warplink codespam}}
+~~DISCUSSION~~

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