Merge pull request below#56 from mstorsjo/neon-fix

Avoid using nonstandard assembly syntax for NEON

Author: below

Chapter 13/matrixmultneon.s

@@ -34,9 +34,9 @@ main:
 	LDR	D5, [X0]
 
 .macro mulcol ccol bcol
-	MUL.4H	\ccol\(), V0, \bcol\()[0]
-	MLA.4H	\ccol\(), V1, \bcol\()[1]
-	MLA.4H	\ccol\(), V2, \bcol\()[2]
+	MUL	\ccol\().4H, V0.4H, \bcol\().H[0]
+	MLA	\ccol\().4H, V1.4H, \bcol\().H[1]
+	MLA	\ccol\().4H, V2.4H, \bcol\().H[2]
 .endm
 
 	mulcol	V6, V3	// process first column

README.md

@@ -335,17 +335,11 @@ Like in Chapter 11, all the chages have been introduced already. Nothing new her
 
 ## Chapter 13: Neon Coprocessor
 
-Once again, the Clang assembler wants a slightly different syntax: Where gcc accepts
-
-```
-MUL V6.4H, V0.4H, V3.4H[0]
-```
-
-the Clang assembler expects
-
-```
-MUL.4H V6, V0, V3[0]
-```
+The example used a nonstandard syntax for referencing a single vector element,
+which GNU assembler accepts, but Clang doesn't.
+Where the example used `V3.4H[0]` for referencing the first 16 bit element,
+the correct, standard syntax is `V3.H[0]`, which is accepted both by GNU
+assembler and Clang.
 
 All other changes to the code should be trivial at this point.