1 files changed, 28 insertions, 0 deletions
diff --git a/kern/cpu_number.c b/kern/cpu_number.c
new file mode 100644
index 00000000..0b2e2f1c
--- /dev/null
+++ b/kern/cpu_number.c
@@ -0,0 +1,28 @@
+int apic2kernel[255];
+int cpu_number_start = 0, cpu_number_counter = 0;
+
+int cpu_number(void) {
+  int eax = 1, ebx = 0, ecx = 0, edx = 0;
+  unsigned int i = 0;
+  int apic_id = 0;
+
+  if (!cpu_number_start) {
+    for (i = 0; i < 255; i++) {
+      apic2kernel[i] = -1;
+    }
+    cpu_number_start = 1;
+  }
+
+  asm("cpuid" : "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx) : "a" (eax));
+  apic_id = (char) (ebx >> 24) & 0xff;
+  //printf("apic_id = %d\n", apic_id);
+
+  if (apic2kernel[apic_id] != -1) {
+    return apic2kernel[apic_id];
+  } else {
+    apic2kernel[apic_id] = cpu_number_counter;
+    cpu_number_counter++;
+  }
+
+  return apic2kernel[apic_id];
+}