1 files changed, 79 insertions, 0 deletions
diff --git a/tmk_core/common/wait.h b/tmk_core/common/wait.h
index 89128e9daf..28224fe3aa 100644
--- a/tmk_core/common/wait.h
+++ b/tmk_core/common/wait.h
@@ -6,10 +6,89 @@
 extern "C" {
 #endif
 
+#if defined(__ARMEL__) || defined(__ARMEB__)
+#    ifndef __OPTIMIZE__
+#        pragma message "Compiler optimizations disabled; wait_cpuclock() won't work as designed"
+#    endif
+
+#    define wait_cpuclock(x) wait_cpuclock_allnop(x)
+
+#    define CLOCK_DELAY_NOP8 "nop\n\t nop\n\t nop\n\t nop\n\t   nop\n\t nop\n\t nop\n\t nop\n\t"
+
+__attribute__((always_inline)) static inline void wait_cpuclock_allnop(unsigned int n) { /* n: 1..135 */
+    /* The argument n must be a constant expression.
+     * That way, compiler optimization will remove unnecessary code. */
+    if (n < 1) {
+        return;
+    }
+    if (n > 8) {
+        unsigned int n8 = n / 8;
+        n               = n - n8 * 8;
+        switch (n8) {
+            case 16:
+                asm volatile(CLOCK_DELAY_NOP8::: "memory");
+            case 15:
+                asm volatile(CLOCK_DELAY_NOP8::: "memory");
+            case 14:
+                asm volatile(CLOCK_DELAY_NOP8::: "memory");
+            case 13:
+                asm volatile(CLOCK_DELAY_NOP8::: "memory");
+            case 12:
+                asm volatile(CLOCK_DELAY_NOP8::: "memory");
+            case 11:
+                asm volatile(CLOCK_DELAY_NOP8::: "memory");
+            case 10:
+                asm volatile(CLOCK_DELAY_NOP8::: "memory");
+            case 9:
+                asm volatile(CLOCK_DELAY_NOP8::: "memory");
+            case 8:
+                asm volatile(CLOCK_DELAY_NOP8::: "memory");
+            case 7:
+                asm volatile(CLOCK_DELAY_NOP8::: "memory");
+            case 6:
+                asm volatile(CLOCK_DELAY_NOP8::: "memory");
+            case 5:
+                asm volatile(CLOCK_DELAY_NOP8::: "memory");
+            case 4:
+                asm volatile(CLOCK_DELAY_NOP8::: "memory");
+            case 3:
+                asm volatile(CLOCK_DELAY_NOP8::: "memory");
+            case 2:
+                asm volatile(CLOCK_DELAY_NOP8::: "memory");
+            case 1:
+                asm volatile(CLOCK_DELAY_NOP8::: "memory");
+            case 0:
+                break;
+        }
+    }
+    switch (n) {
+        case 8:
+            asm volatile("nop" ::: "memory");
+        case 7:
+            asm volatile("nop" ::: "memory");
+        case 6:
+            asm volatile("nop" ::: "memory");
+        case 5:
+            asm volatile("nop" ::: "memory");
+        case 4:
+            asm volatile("nop" ::: "memory");
+        case 3:
+            asm volatile("nop" ::: "memory");
+        case 2:
+            asm volatile("nop" ::: "memory");
+        case 1:
+            asm volatile("nop" ::: "memory");
+        case 0:
+            break;
+    }
+}
+#endif
+
 #if defined(__AVR__)
 #    include <util/delay.h>
 #    define wait_ms(ms) _delay_ms(ms)
 #    define wait_us(us) _delay_us(us)
+#    define wait_cpuclock(x) __builtin_avr_delay_cycles(x)
 #elif defined PROTOCOL_CHIBIOS
 #    include <ch.h>
 #    define wait_ms(ms)                     \