hl = a + {0-255}

1 files changed, 19 insertions, 0 deletions

diff --git a/Optimizing-assembly-code.md b/Optimizing-assembly-code.md
index 8f18570..5d80acf 100644
--- a/Optimizing-assembly-code.md
+++ b/Optimizing-assembly-code.md
@@ -35,6 +35,7 @@ WikiTI's advice fully applies here:
   - [Add `a` to a 16-bit register](#add-a-to-a-16-bit-register)
   - [Subtract an 8-bit constant from a 16-bit register](#subtract-an-8-bit-constant-from-a-16-bit-register)
   - [Set a 16-bit register to `a` plus a 16-bit constant](#set-a-16-bit-register-to-a-plus-a-16-bit-constant)
+  - [Set a 16-bit register to `a` plus a nonzero 8-bit constant](#set-a-16-bit-register-to-a-plus-a-nonzero-8-bit-constant)
   - [Set a 16-bit register to `a` \* 16](#set-a-16-bit-register-to-a--16)
   - [Increment or decrement a 16-bit register](#increment-or-decrement-a-16-bit-register)
   - [Load from an address to `hl`](#load-from-an-address-to-hl)
@@ -861,6 +862,24 @@ But do:
 ```
 
 
+### Set a 16-bit register to `a` plus a nonzero 8-bit constant
+
+(The example uses `hl`, but `bc` or `de` would also work.)
+
+Don't do any of [the above](#set-a-16-bit-register-to-a-plus-a-16-bit-constant) methods for a 16-bit constant. Instead, do:
+
+```asm
+	; 6 bytes, 6 cycles
+	sub -FOO
+	ld l, a
+	sbc a
+	inc a
+	ld h, a
+```
+
+This will work for any constant `FOO` from 1 to 255, but not 0.
+
+
 ### Set a 16-bit register to `a` \* 16
 
 (The example uses `hl`, but `bc` or `de` would also work.)