Basic frequency calculation

src/commands.asm

@@ -250,25 +250,33 @@ sysinfo_command:
 
     ; rbx = max_frequency
 
-    mov eax, 0x06
-    cpuid
-    and ecx, 1b
-    test ecx, ecx
-    je .last
-
     call goto_next_line
 
     mov r8, sysinfo_current_frequency
     mov r9, sysinfo_current_frequency_length
     call print_normal
 
-    ; read MPERF
-    mov rcx, 0xe7
-    rdmsr
+    rdtscp
+    shl rdx, 32
+    or rax, rdx
+    mov rcx, rax ; cycles start
 
-    ; read APERF
-    mov rcx, 0xe8
-    rdmsr
+    mov r8, 100
+    call wait_ms ; wait 100ms
+
+    rdtscp
+    shl rdx, 32
+    or rax, rdx ; cycles end
+
+    sub rax, rcx ; cycles
+    imul rax, 10
+
+    xor rdx, rdx
+    mov rcx, 1000000
+    div rcx
+
+    mov r8, rax
+    call print_int_normal
 
     .last:
 

src/timer.asm

@@ -20,6 +20,9 @@ install_timer:
 
 irq_timer_handler:
     push rax
+    push rbx
+    push rcx
+    push rdx
 
     mov rax, [timer_ticks]
     inc rax
@@ -37,7 +40,39 @@ irq_timer_handler:
 
     .end:
 
-    pop r8
+    pop rdx
+    pop rcx
+    pop rbx
+    pop rax
+
+    ret
+
+; in r8: milliseconds to wait
+wait_ms:
+    push r9
+    push r10
+
+    mov r9, [timer_ticks]
+    add r9, r8
+
+    .start:
+        cli
+        mov r10, [timer_ticks]
+        cmp r10, r9
+        je .done
+        sti
+        nop
+        nop
+        nop
+        nop
+        nop
+        nop
+        jmp .start
+
+    .done:
+
+    pop r10
+    pop r9
 
     ret