From f9bc3d6248f5d3192bbe863db0468b6b5202caf1 Mon Sep 17 00:00:00 2001
From: Abel Romero Pérez <romeroperezabel@gmail.com>
Date: Thu, 28 Jun 2018 00:04:07 -0400
Subject: initial commit

---
 .gitignore             |  3 +++
 i386/i386/cpu_number.S |  4 ++++
 kern/cpu_number.c      | 28 ++++++++++++++++++++++++++++
 3 files changed, 35 insertions(+)
 create mode 100644 i386/i386/cpu_number.S
 create mode 100644 kern/cpu_number.c

diff --git a/.gitignore b/.gitignore
index 92fc6e7f..1a75fccc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -50,3 +50,6 @@ build-aux/
 /doc/mach.toc
 /doc/mach.tp
 /doc/mach.vr
+/build
+Makefile.am.orig
+Makefile.am.rej
diff --git a/i386/i386/cpu_number.S b/i386/i386/cpu_number.S
new file mode 100644
index 00000000..95036b8b
--- /dev/null
+++ b/i386/i386/cpu_number.S
@@ -0,0 +1,4 @@
+.macro CPU_NUMBER reg
+ call cpu_number
+ movl %eax, \reg
+.endm
diff --git a/kern/cpu_number.c b/kern/cpu_number.c
new file mode 100644
index 00000000..324ed752
--- /dev/null
+++ b/kern/cpu_number.c
@@ -0,0 +1,28 @@
+int apic2kernel[255];
+int cpu_number_start = 0, cpu_number_counter = 0;
+
+static 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];
+}
-- 
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