ax6's trick

1 files changed, 15 insertions, 23 deletions

diff --git a/Optimizing-assembly-code.md b/Optimizing-assembly-code.md
index 5d80acf..9933b84 100644
--- a/Optimizing-assembly-code.md
+++ b/Optimizing-assembly-code.md
@@ -35,7 +35,6 @@ 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)
@@ -679,21 +678,21 @@ But do:
 Don't do:
 
 ```asm
-	ld a, [hFoo] ; 3 bytes, 4 cycles
+	ld a, [hFoobar] ; 3 bytes, 4 cycles
 ```
 
 ```asm
-	ld [hFoo], a ; 3 bytes, 4 cycles
+	ld [hFoobar], a ; 3 bytes, 4 cycles
 ```
 
 But do:
 
 ```asm
-	ldh a, [hFoo] ; 2 bytes, 3 cycles
+	ldh a, [hFoobar] ; 2 bytes, 3 cycles
 ```
 
 ```asm
-	ldh [hFoo], a ; 2 bytes, 3 cycles
+	ldh [hFoobar], a ; 2 bytes, 3 cycles
 ```
 
 
@@ -784,7 +783,7 @@ Don't do:
 ```asm
 	; 8 bytes, 8 cycles
 	ld a, l
-	sub FOO
+	sub FOOBAR
 	ld l, a
 	ld a, h
 	sbc 0
@@ -796,7 +795,7 @@ But do:
 ```asm
 	; 7 bytes, 7 or 8 cycles
 	ld a, l
-	sub FOO
+	sub FOOBAR
 	ld l, a
 	jr nc, .no_carry
 	dec h
@@ -807,7 +806,7 @@ Or if you can spare another 16-bit register, do:
 
 ```asm
 	; 4 bytes, 5 cycles
-	ld de, -FOO
+	ld de, -FOOBAR
 	add hl, de
 ```
 
@@ -822,7 +821,7 @@ Don't do:
 	; 7 bytes, 8 cycles; uses another 16-bit register
 	ld e, a
 	ld d, 0
-	ld hl, Address
+	ld hl, FooBar
 	add hl, de
 ```
 
@@ -830,7 +829,7 @@ And don't do:
 
 ```asm
 	; 8 bytes, 8 cycles
-	ld hl, Address
+	ld hl, FooBar
 	add l
 	ld l, a
 	adc h
@@ -842,8 +841,8 @@ And don't do:
 
 ```asm
 	; 8 bytes, 7 or 8 cycles
-	ld h, HIGH(Address)
-	add LOW(Address)
+	ld h, HIGH(FooBar)
+	add LOW(FooBar)
 	ld l, a
 	jr nc, .no_carry
 	inc h
@@ -854,31 +853,24 @@ But do:
 
 ```asm
 	; 7 bytes, 7 cycles
-	add LOW(Address)
+	add LOW(FooBar)
 	ld l, a
-	adc HIGH(Address)
+	adc HIGH(FooBar)
 	sub l
 	ld h, a
 ```
 
-
-### 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:
+And if the constant is 8-bit and nonzero (i.e. 0 < `FooBar` < 256), then do:
 
 ```asm
 	; 6 bytes, 6 cycles
-	sub -FOO
+	sub LOW(-FooBar)
 	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