1 files changed, 65 insertions, 0 deletions
diff --git a/asm2.c b/asm2.c
new file mode 100644
index 0000000..7621b78
--- /dev/null
+++ b/asm2.c
@@ -0,0 +1,65 @@
+/*
+ * So far I cannot figure out how I used to compile this :/
+ * asm(".intel_syntax prefix");
+ *
+ */
+
+#include <stdio.h>
+
+void asm_summation(int *n)
+{
+    asm("xor eax, eax  \n" /* summation */
+        "mov ecx, 0    \n" /* counter */
+        "mov edx, %0   \n" /* end */
+        "_loop:        \n"
+        "add eax, ecx  \n"
+        "inc ecx       \n"
+        "cmp ecx, edx  \n"
+        "jle _loop     \n"
+        "mov %0, eax   \n" : "=r" (*n) : "r" (*n) : "eax");
+}
+
+void asm_summation2(int *n)
+{
+    if (*n <= 1)
+    {
+        *n = 0;
+        return;
+    }
+
+    asm("xor eax, eax  \n" /* summation */
+        "mov ecx, %0   \n" /* counter */
+        "_loop2:       \n"
+        "add eax, ecx  \n"
+        "loop _loop2   \n"
+        "mov %0, eax   \n" : "=r" (*n) : "r" (*n) : "eax");
+}
+
+void asm_rotate(int *n)
+{
+    asm("mov eax, %0   \n"
+        "rol eax, 1    \n"
+        "mov %0, eax   \n" : "=r" (*n) : "r" (*n) : "eax");
+}
+
+int main(int argc, char *argv[])
+{
+    int i = 12;
+
+
+
+    /* output, input (r) = register, clobbered */
+    asm("mov eax, %0\n" : : "r" (i) : "eax");
+    printf("i is: %d\n", i);
+
+    int j = -1;
+    asm_summation2(&j);
+    printf("summation is %d\n", j);
+
+    int k = 2;
+    asm_rotate(&k);
+    printf("k = %d\n", k);
+
+    return 0;
+}
+