Added unit conversion macros

PD uses odd units for voltages and currents.  Power too, but we don't
work with power (yet).  In the shell, we have to convert to and from
these odd units.  We had been doing this in-place every time, which was
a bit crumby.  Now it's done with macros in pd.h, making prettier and
more maintainable code.

src/pd.h

 #define PD_T_TYPEC_SINK_WAIT_CAP MS2ST(465)
 
 
+/*
+ * Unit conversions
+ *
+ * V: volt
+ * CV: centivolt
+ * MV: millivolt
+ * PDV: Power Delivery voltage unit (50 mV)
+ * A: ampere
+ * CA: centiampere
+ * MA: milliampere
+ * PDI: Power Delivery current unit (10 mA)
+ */
+#define PD_MV2PDV(mv) ((mv) / 50)
+#define PD_PDV2MV(pdv) ((pdv) * 50)
+#define PD_MA2PDI(ma) ((ma) / 10)
+#define PD_PDI2MA(pdi) ((pdi) * 10)
+
+/* Get portions of a PD voltage in more normal units */
+#define PD_PDV_V(pdv) ((pdv) / 20)
+#define PD_PDV_CV(pdv) (5 * ((pdv) % 20))
+
+/* Get portions of a PD current in more normal units */
+#define PD_PDI_A(pdv) ((pdv) / 100)
+#define PD_PDI_CA(pdv) ((pdv) % 100)
+
+
+
 #endif /* PDB_PD_H */

src/shell.c

 #include <stdlib.h>
 #include <string.h>
 
-#include <ch.h>
-
 #include "chprintf.h"
 
 #include "usbcfg.h"
 #include "storage.h"
 #include "led.h"
+#include "pd.h"
 
 
 /* Buffer for unwritten configuration */
     if (i >= 0 && i <= UINT16_MAX && endptr > argv[0]) {
         tmpcfg.status = PDB_CONFIG_STATUS_VALID;
         /* Convert mV to the unit used by USB PD */
-        /* XXX this could use a macro */
-        tmpcfg.v = i / 50;
+        tmpcfg.v = PD_MV2PDV(i);
     } else {
         chprintf(chp, "Invalid voltage\r\n");
         return;
     if (i >= 0 && i <= UINT16_MAX && endptr > argv[0]) {
         tmpcfg.status = PDB_CONFIG_STATUS_VALID;
         /* Convert mA to the unit used by USB PD */
-        /* XXX this could use a macro */
-        tmpcfg.i = i / 10;
+        tmpcfg.i = PD_MA2PDI(i);
     } else {
         chprintf(chp, "Invalid current\r\n");
         return;

src/storage.c

 
 #include "chprintf.h"
 
+#include "pd.h"
+
 
 struct pdb_config *pdb_config_array = (struct pdb_config *) PDB_CONFIG_BASE;
 
     chprintf(chp, "\r\n");
 
     /* Print voltages and current */
-    chprintf(chp, "v: %d.%02d V\r\n", cfg->v/20, 5*(cfg->v%20));
-    chprintf(chp, "i: %d.%02d A\r\n", cfg->i/100, cfg->i%100);
+    chprintf(chp, "v: %d.%02d V\r\n", PD_PDV_V(cfg->v), PD_PDV_CV(cfg->v));
+    chprintf(chp, "i: %d.%02d A\r\n", PD_PDI_A(cfg->i), PD_PDI_CA(cfg->i));
     if (cfg->flags & PDB_CONFIG_FLAGS_VAR_BAT) {
-        chprintf(chp, "v_min: %d.%02d V\r\n", cfg->v_min/20, 5*(cfg->v_min%20));
-        chprintf(chp, "v_max: %d.%02d V\r\n", cfg->v_max/20, 5*(cfg->v_max%20));
+        chprintf(chp, "v_min: %d.%02d V\r\n", PD_PDV_V(cfg->v_min),
+                 PD_PDV_CV(cfg->v_min));
+        chprintf(chp, "v_max: %d.%02d V\r\n", PD_PDV_V(cfg->v_max),
+                 PD_PDV_CV(cfg->v_max));
     }
 }