procedures

5 files changed, 150 insertions, 0 deletions

diff --git a/3/6_control/27_while_for.c b/3/6_control/27_while_for.c
new file mode 100644
index 0000000..f7f73f7
--- /dev/null
+++ b/3/6_control/27_while_for.c
@@ -0,0 +1,46 @@
+#include <stdio.h>
+
+long fact_for(long n) {
+    long i;
+    long result = 1;
+    for (i = 2; i <= n; i++) {
+        result *= i;
+    }
+    return result;
+}
+
+// guarded do
+//
+// init-s
+// t = test-e;
+// if (!t) goto done;
+//
+// loop:
+//   body-s
+//   update-e;
+//   t = test-e;
+//   if (t) goto loop;
+//
+// done:
+
+long fact_for_gd_goto(long n) {
+    long i = 2;
+    long result = 1;
+
+    int t = i<=n;
+    if (!t) {
+        goto done;
+    }
+loop:
+    result *= i;
+    i++;
+    t = i<=n;
+    if (t) goto loop;
+done:
+    return result;
+}
+
+int main() {
+    printf("for: %ld, goto: %ld\n", fact_for(5), fact_for_gd_goto(5));
+    return 0;
+}
diff --git a/3/6_control/28_fun_b.c b/3/6_control/28_fun_b.c
new file mode 100644
index 0000000..5ecf7d2
--- /dev/null
+++ b/3/6_control/28_fun_b.c
@@ -0,0 +1,33 @@
+#include <stdio.h>
+
+//  x in rdi
+//  fun_b:
+//      movl    $64, %edx   i <- 64  (32 bits?, long presumably)
+//      movl    $0, %eax    val <- 0
+//  .L10:
+//      movq    %rdi, %rcx  tmp <- x
+//      andl    $1, %ecx    tmp <- tmp & 1
+//      addq    %rax, %rax  val <- val + val
+//      orq     %rcx, %rax  val <- val | tmp
+//      shrq    %rdi
+//      subq    $1, %rdx    i <- i-1
+//      jne     .L10        if i != 0 then goto .L10
+//      rep; ret
+long fun_b(unsigned long x) {
+    long val = 0;
+    long i;
+    for (i = 64; i!=0; i--) {
+        long tmp = x;
+        tmp &= 1; // check 1 bit
+        val += val; // multiply by two
+        val |= tmp; // add 1 bit if present
+        x >>= 1;    // shift next bit into 1 bit
+    }
+    return val;
+}
+
+// Seems to compute the value shifted to the left (63 - nbit), (or in other words the mirror image)
+int main() {
+    printf("val: %ld, computed: %ld, bits: %lb\n", fun_b(10), (long) 10 << 59, 10);
+    return 0;
+}
diff --git a/3/6_control/29_continue.c b/3/6_control/29_continue.c
new file mode 100644
index 0000000..175f57b
--- /dev/null
+++ b/3/6_control/29_continue.c
@@ -0,0 +1,5 @@
+#include <stdio.h>
+
+int main() {
+    return 0;
+}
diff --git a/3/6_control/30_switch2.c b/3/6_control/30_switch2.c
new file mode 100644
index 0000000..0c8cc85
--- /dev/null
+++ b/3/6_control/30_switch2.c
@@ -0,0 +1,37 @@
+#include <stdio.h>
+
+// x in %rdi
+// switch2:
+//   addq   $1, %rdi
+//   cmpq   $8, %rdi
+//   ja     .L2     if (x + 1) > 8 then goto default
+//   jmp    *.L4(,%rdi,8)   take the address at x*8 from .L4
+void switch2(long x, long *dest) {
+    long val = 0;
+    switch (x) {
+        case -1:
+            printf(".L9");
+            break;
+        case 0:
+        case 7:
+            printf(".L5");
+            break;
+        case 1:
+            printf(".L6");
+            break;
+        case 2:
+        case 4:
+            printf(".L7");
+            break;
+        case 5:
+            printf(".L8");
+            break;
+
+    }
+    *dest = val;
+}
+
+int main(void) {
+    printf("val: %ld\n");
+    return 0;
+}
diff --git a/3/6_control/31_the_switcher.c b/3/6_control/31_the_switcher.c
new file mode 100644
index 0000000..c8b0a4a
--- /dev/null
+++ b/3/6_control/31_the_switcher.c
@@ -0,0 +1,29 @@
+#include <stdio.h>
+
+// a in %rdi, b in %rsi, c in %rdx, dest in %rcx
+void switcher(long a, long b, long c, long *dest) {
+    long val;
+    switch (a) {
+        case 5: /* Case A .L7 */
+            c = 15 ^ a;
+            /* Fall through */
+        case 0: /* Case B .L3 */
+            val = 112 + c;
+            break;
+        case 2: /* Case C .L5 */
+        case 7: /* Case D .L5 */
+            val = (c + b)<<2;
+            break;
+        case 4: /* Case E */
+            val = a;
+            break;
+        default: /* .L2 */
+            val = b;
+    }
+    *dest = val; /* .L6 */
+}
+
+int main(void) {
+    printf("val: %ld\n");
+    return 0;
+}