basic command implementation traditional way

[cortex-from-scratch] / lib / regfunc.c

diff --git a/lib/regfunc.c b/lib/regfunc.c
index f5bc539..2e24689 100644 (file)
--- a/lib/regfunc.c
+++ b/lib/regfunc.c
@@ -17,8 +17,10 @@
 #include <lib/string.h>
 #include <lib/stdio.h>
 
-#include <sys/mmap.h>
+#include <lib/tinyprintf.h>
 
+#include <sys/mmap.h>
+#include <sys/robsys.h>
 
 // register set bit at position
 void rsetbit(volatile uint32_t * reg, short pos) {
@@ -48,38 +50,6 @@ void rwrite(volatile uint32_t * reg, uint32_t val) {
 }
 
 
-/* DEPRECATED write value (uint8_t) to register 
-void regw_u8(volatile uint32_t * reg, uint8_t val, short shift, short flag) {
-
-       switch(flag) {
-               case OWRITE:
-                       *reg = (val << shift);
-                       break;
-               case SETBIT:
-                       *reg = *reg | (val << shift);
-                       break;
-               case CLRBIT:
-                       *reg = *reg & ~(val << shift);
-                       break;
-       }
-} */
-
-/* DEPRECATED write value (uint32_t) to register 
-void regw_u32(volatile uint32_t * reg, uint32_t val, short shift, short flag) {
-
-       switch(flag) {
-               case OWRITE:
-                       *reg = (val << shift);
-                       break;
-               case SETBIT:
-                       *reg = *reg | (val << shift);
-                       break;
-               case CLRBIT:
-                       *reg = *reg & ~(val << shift);
-                       break;
-       }
-} */
-
 /* Deprecated use printf instead
 char hexbuf[8];
 char * regtohex(uint32_t addr) {
@@ -127,3 +97,26 @@ uint32_t hextoreg(char * a) {
 
 }
 
+/* Busy-loop block implementation. Each iteration will take 3 CPU cycles.
+ * Of course, when interrupts are enabled, the exact delay time will be 
+ * uncertain. 
+ *
+ * Example: for a standard STM32x config board (8MHz) the maximum delay is
+ * 0xFFFF * (1/8,000,000) * 3 = 24.58ms 
+ * */
+static void __block(uint16_t count) {
+
+       asm volatile("b1: subs %0, %1, #1" "\n\t"
+               "bne b1" : "=r" (count) : "r" (count));
+}
+
+/* Delay us microsecond
+ * Note: delay includes setup time (about 4 clockcycles), so is quite
+ * inaccurate  */
+void _block(uint16_t us) {
+       
+       uint16_t count = (us/3) * CLKSPEED_MHZ; // x cycles 
+       __block(count);
+
+}
+