Add picocalc stm32 i2c keyboard code

Code/picocalc_keyboard/reg.ino

@@ -0,0 +1,45 @@
+#include "reg.h"
+
+static uint8_t regs[REG_ID_LAST];
+
+uint8_t reg_get_value(enum reg_id reg)
+{
+  return regs[reg];
+}
+
+void reg_set_value(enum reg_id reg, uint8_t value)
+{
+  regs[reg] = value;
+}
+
+bool reg_is_bit_set(enum reg_id reg, uint8_t bit)
+{
+  return regs[reg] & bit;
+}
+
+void reg_set_bit(enum reg_id reg, uint8_t bit)
+{
+  regs[reg] |= bit;
+}
+
+/*
+ * | Bit    | Name             | Description                                                        |
+| ------ |:----------------:| ------------------------------------------------------------------:|
+| 7      | CFG_USE_MODS     | Should Alt, Sym and the Shift keys modify the keys being reported. |
+| 6      | CFG_REPORT_MODS  | Should Alt, Sym and the Shift keys be reported as well.            |
+| 5      | CFG_PANIC_INT    | Currently not implemented.                                         |
+| 4      | CFG_KEY_INT      | Should an interrupt be generated when a key is pressed.            |
+| 3      | CFG_NUMLOCK_INT  | Should an interrupt be generated when Num Lock is toggled.         |
+| 2      | CFG_CAPSLOCK_INT | Should an interrupt be generated when Caps Lock is toggled.        |
+| 1      | CFG_OVERFLOW_INT | Should an interrupt be generated when a FIFO overflow happens.     |
+| 0      | CFG_OVERFLOW_ON  | When a FIFO overflow happens, should the new entry still be pushed, overwriting the oldest one. If 0 then new entry is lost. |
+ */
+void reg_init(void)
+{
+  regs[REG_ID_CFG] = CFG_OVERFLOW_INT | CFG_KEY_INT | CFG_USE_MODS|CFG_REPORT_MODS ;
+  regs[REG_ID_DEB] = 10;
+  regs[REG_ID_FRQ] = 5;
+  regs[REG_ID_BKL] = 255;//100%duty
+  regs[REG_ID_BK2] = 0;
+  regs[REG_ID_BAT] = 0xff; //default .no battery 
+}