Update codegen README to mention new multiply_add function.

font-codegen/README.md

@@ -200,8 +200,8 @@ The following annotations are supported on top-level objects:
   in a table), the name of a field (preceded by the `$` token) or a literal
   integer. The less-simple form begins with a function identifier, and then one
   or more arguments, comma separated. Currently accepted function identifiers
-  are 'add', 'subtract', 'add_multiply', 'half', 'map_delta_size', and
-  'delta_value_count'.
+  are 'add', 'subtract', 'add_multiply', 'multiply_add', 'half', 'map_delta_size',
+  and 'delta_value_count'.
 - `#[compile(arg)]`: If present, this field will not be included in the compile
   type. The value may be either the literal 'skip', or an expression that
   evaluates to the field's type: the skip case is only expected in cases where

font-codegen/src/parsing.rs

@@ -302,7 +302,7 @@ pub(crate) enum CountTransform {
     Add,
     /// requires exactly three args, defined as ($arg1 + $arg2) * $arg3
     AddMul,
-    /// requires exactly three args, defined as ($arg1 * $arg2) + 1
+    /// requires exactly three args, defined as ($arg1 * $arg2) + $arg3
     MulAdd,
     /// requires exactly one arg. defined as $arg1 / 2
     Half,

read-fonts/src/tables/ift.rs

@@ -229,6 +229,7 @@ impl<'a> Iterator for GidToEntryIter<'a> {
 }
 
 impl<'a> GlyphPatches<'a> {
+    /// Returns an iterator over the per glyph data for the table with the given index.
     pub fn glyph_data_for_table(
         &'a self,
         table_index: u32,