- added optimization notes in readme

[dosdemo] / src / util.h

diff --git a/src/util.h b/src/util.h
index f8ae175..6d200b7 100644 (file)
--- a/src/util.h
+++ b/src/util.h
@@ -24,42 +24,53 @@ static INLINE int32_t cround64(double val)
        return *(int32_t*)&val;
 }
 
-uint32_t perf_start_count, perf_interval_count;
+extern uint32_t perf_start_count, perf_interval_count;
 
 #ifdef __WATCOMC__
 void perf_start(void);
 #pragma aux perf_start = \
+       "xor eax, eax" \
+       "cpuid" \
        "rdtsc" \
        "mov [perf_start_count], eax" \
-       modify[eax edx];
+       modify[eax ebx ecx edx];
 
 void perf_end(void);
 #pragma aux perf_end = \
+       "xor eax, eax" \
+       "cpuid" \
        "rdtsc" \
        "sub eax, [perf_start_count]" \
        "mov [perf_interval_count], eax" \
-       modify [eax edx];
+       modify [eax ebx ecx edx];
 #endif
 
 #ifdef __GNUC__
 #define perf_start()  asm volatile ( \
+       "xor %%eax, %%eax\n" \
+       "cpuid\n" \
        "rdtsc\n" \
        "mov %%eax, %0\n" \
-       : "=m"(perf_start_count) :: "%eax", "%edx")
+       : "=m"(perf_start_count) \
+       :: "%eax", "%ebx", "%ecx", "%edx")
 
 #define perf_end() asm volatile ( \
+       "xor %%eax, %%eax\n" \
+       "cpuid\n" \
        "rdtsc\n" \
        "sub %1, %%eax\n" \
        "mov %%eax, %0\n" \
        : "=m"(perf_interval_count) \
        : "m"(perf_start_count) \
-       : "%eax", "%edx")
+       : "%eax", "%ebx", "%ecx", "%edx")
 #endif
 
 #ifdef _MSC_VER
 #define perf_start() \
        do { \
                __asm { \
+                       xor eax, eax \
+                       cpuid \
                        rdtsc \
                        mov [perf_start_count], eax \
                } \
@@ -68,6 +79,8 @@ void perf_end(void);
 #define perf_end() \
        do { \
                __asm { \
+                       xor eax, eax \
+                       cpuid \
                        rdtsc \
                        sub eax, [perf_start_count] \
                        mov [perf_interval_count], eax \