Reduce PROGMEM usage for sendstring LUT (#8109)

* Reduce PROGMEM usage for keycode map

Bit-pack the keycode bool array to gain back a small amount of flash space.
The trade-off is an increase in runtime instructions when running macros.

It does make the code a bit harder to read, as well as maintain.

For configs that use send_string() et al, it saves ~100 bytes.

* Switch to macro and common definition

Rewrite the array declarations so both the unpacked (original) and
packed LUT arrays can use the same value definitions. This is done by
defining a macro that "knows what to do".

This makes the code much easier to read and maintain.

* Fix macro typos and improve perf

Pack the bits in a more efficient order for extraction.
And also fix the copy/paste error in the macro...

* Switch fully to packed LUT

Some minor reformatting.
Compile tested all sendstring_xyz.h to make sure they were converted
properly. Also checked that an unconverted version would generate a
compile error.

* Apply whitespace suggestions from code review

Co-Authored-By: Ryan <fauxpark@gmail.com>

Co-authored-by: Ryan <fauxpark@gmail.com>

1 files changed, 14 insertions, 2 deletions

diff --git a/quantum/quantum.h b/quantum/quantum.h
index 7dc14e628..d03ba5942 100644
--- a/quantum/quantum.h
+++ b/quantum/quantum.h
@@ -211,9 +211,21 @@ typedef ioline_t pin_t;
 #define SEND_STRING(string) send_string_P(PSTR(string))
 #define SEND_STRING_DELAY(string, interval) send_string_with_delay_P(PSTR(string), interval)
 
-extern const bool    ascii_to_shift_lut[128];
-extern const bool    ascii_to_altgr_lut[128];
+// Look-Up Tables (LUTs) to convert ASCII character to keycode sequence.
 extern const uint8_t ascii_to_keycode_lut[128];
+extern const uint8_t ascii_to_shift_lut[16];
+extern const uint8_t ascii_to_altgr_lut[16];
+// clang-format off
+#define KCLUT_ENTRY(a, b, c, d, e, f, g, h) \
+    ( ((a) ? 1 : 0) << 0 \
+    | ((b) ? 1 : 0) << 1 \
+    | ((c) ? 1 : 0) << 2 \
+    | ((d) ? 1 : 0) << 3 \
+    | ((e) ? 1 : 0) << 4 \
+    | ((f) ? 1 : 0) << 5 \
+    | ((g) ? 1 : 0) << 6 \
+    | ((h) ? 1 : 0) << 7 )
+// clang-format on
 
 void send_string(const char *str);
 void send_string_with_delay(const char *str, uint8_t interval);