_s7 keyword generator

KeywordHasher.h

@@ -54,4 +54,43 @@ static_assert("MAIN"_hk == 11339,"Keyword hasher error");
 static_assert("SLOW"_hk == -17209,"Keyword hasher error");
 static_assert("SPEED28"_hk == -17064,"Keyword hasher error");
 static_assert("SPEED128"_hk == 25816,"Keyword hasher error");
+
+// Compile time converter from "abcd"_s7  to the 7 segment nearest equivalent
+
+constexpr uint8_t seg7Digits[]={
+      0b00111111,0b00000110,0b01011011,0b01001111, // 0..3
+      0b01100110,0b01101101,0b01111101,0b00000111, // 4..7
+      0b01111111,0b01101111 // 8..9
+    };
+    
+constexpr uint8_t seg7Letters[]={
+        0b01110111,0b01111100,0b00111001,0b01011110, // ABCD
+        0b01111001,0b01110001,0b00111101,0b01110110, // EFGH 
+        0b00000100,0b00011110,0b01110010,0b00111000,  //IJKL
+        0b01010101,0b01010100,0b01011100,0b01110011, // MNOP
+        0b10111111,0b01010000,0b01101101,0b01111000, // QRST
+        0b00111110,0b00011100,0b01101010,0b01001001,  //UVWX
+        0b01100110,0b01011011  //YZ
+    };
+constexpr uint8_t seg7Space=0b00000000;
+constexpr uint8_t seg7Minus=0b01000000;
+constexpr uint8_t seg7Equals=0b01001000;
+    
+
+constexpr uint32_t CompiletimeSeg7(const char *  sv, uint32_t running, size_t rlen) {
+    return (*sv==0 || rlen==0) ? running << (8*rlen) : CompiletimeSeg7(sv+1,
+          (*sv >= '0' && *sv <= '9') ? (running<<8) | seg7Digits[*sv-'0'] : 
+          (*sv >= 'A' && *sv <= 'Z') ? (running<<8) | seg7Letters[*sv-'A'] : 
+          (*sv >= 'a' && *sv <= 'z') ? (running<<8) | seg7Letters[*sv-'a'] : 
+          (*sv == '-') ? (running<<8) | seg7Minus : 
+          (*sv == '=') ? (running<<8) | seg7Equals : 
+                         (running<<8) | seg7Space,
+          rlen-1               
+        );  // 
+}
+
+constexpr uint32_t operator""_s7(const char * keyword, size_t len) 
+{
+    return  CompiletimeSeg7(keyword,0*len,4);
+}
 #endif

Release_Notes/TM1638.md

@@ -61,6 +61,24 @@ Format values:
        SEG7(500,0xdeadbeef,8X) 
         writes dEAdbEEF to all 8 digits. 
 
-    (RAW example to follow)
-              
+    Writing raw segment patters requires knowledge of the bit pattern to segment relationship:
+`      0
+    == 0 ==
+   5|     | 1
+    == 6 ==
+  4 |     | 2
+    == 3 ==  
+            7=decimal point
+
+            Thus Letter A is segments  6 5 4 2 1 0, in bits  that is (0 bit on right)          
+               0b01110111  or 0x77
+    This is not easy to do my hand and thus a new string type suffix has been introduced to make simple text messages. Note that the HAL interface only has width for 32 bits which is only 4 symbols so writing 8 digits requires two calls.
+
+    e.g.  SEG7(500,"Hell"_s7,4R) SEG7(504,"o"_s7,4R)
+          DELAY(1000)
+          SEG7(500,"Worl"_s7,4R) SEG7(504,"d"_s7,4R)
+
+    Note that some letters like k,m,v,x do not have particularly readable 7-segment representations. 
+                     
+    Credit to https://github.com/dvarrel/TM1638 for the basic formulae.