From 19b1d6ab35898a88801a3e6bbb4baf863912a4ca Mon Sep 17 00:00:00 2001
From: Matt Strapp <matt@mattstrapp.net>
Date: Mon, 27 Sep 2021 21:18:14 -0500
Subject: commit work done

Signed-off-by: Matt Strapp <matt@mattstrapp.net>
---
 csci5271/hw1/hw1markup.md  | 43 ---------------------
 csci5271/hw1/hw1writeup.md | 96 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 96 insertions(+), 43 deletions(-)
 delete mode 100644 csci5271/hw1/hw1markup.md
 create mode 100644 csci5271/hw1/hw1writeup.md

diff --git a/csci5271/hw1/hw1markup.md b/csci5271/hw1/hw1markup.md
deleted file mode 100644
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--- a/csci5271/hw1/hw1markup.md
+++ /dev/null
@@ -1,43 +0,0 @@
-# Homework 1
-## Q1
-
-## Q2
-### A: Perl
-After adding a name to the request, add a semicolon followed by the command. The semicolon is the shell command separator which allows it to parse commands.
-#### Example Request
-```
-"?field-name=;perl+-e+'`command`'"
-```
-### B: C
-
-## Q3
-
-## Q4
-### A
-#### Mistake 1a: Potentially overloading the array
-If the function is called with `to` larger than outer bound of the array, there is a buffer overflow that happens. For example, running it by default with an array of size 10 with a `to` of size 11 on gcc 11.1 causes it to crash because of stack smashing.
-##### Mistake 1b: Underloading the array
-If the function is called with `from` smaller than 0 will cause some values of the array to be replaced with other values from memory. It did not crash, but it is not the intended behavior.
-#### Mistake 2:
-
-#### Mistake 3:
-
-### B: Same Signature
-```c
-    void reverse_range(int *a, int from, int to) {
-        
-```
-### C: Different Signature
-```c
-    int* reverse_range(int arr[], int arrSize, int from, int to) {
-        if (from < 0 || to >= arrSize)
-            return NULL;
-        for (int i = from; i < to; i++) {
-            int temp = arr[i];
-            arr[i] = arr[to];
-            arr[to] = temp;
-            to--;
-        }
-        return arr;
-```
-## Q5
\ No newline at end of file
diff --git a/csci5271/hw1/hw1writeup.md b/csci5271/hw1/hw1writeup.md
new file mode 100644
index 0000000..091f4aa
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+++ b/csci5271/hw1/hw1writeup.md
@@ -0,0 +1,96 @@
+# Homework 1
+
+## Q1
+
+
+
+## Q2
+
+### A: Perl
+
+After adding a name to the request, add a semicolon followed by the command. The semicolon is the shell command separator which allows it to parse commands.
+
+#### Example Request
+
+```
+"?field-name=;perl+-e+'`command`'"
+```
+
+### B: C
+
+## Q3
+
+## Q4
+
+### A
+
+#### Mistake 1a: Potentially overloading the array
+
+If the function is called with `to` larger than outer bound of the array, there is a buffer overflow that happens. For example, running it by default with an array of size 10 with a `to` of 11 on gcc 11.1 causes it to crash because of stack smashing.
+
+##### Mistake 1b: Underloading the array
+
+If the function is called with `from` smaller than 0 will cause some values of the array to be replaced with other values from memory addresses nearby. It did not crash, but it is not the intended behavior.
+
+#### Mistake 2
+
+a
+
+#### Mistake 3
+
+### B: Same Signature
+
+```c
+void reverse_range(int *a, int from, int to) {
+    unsigned int *p = &a[from];
+    unsigned int *q = &a[to];
+/* Until the pointers move past each other: */
+    while (!(p == q + 1 || p == q + 2)) {
+/* Swap *p with *q, without using a temporary variable */
+        *p += *q; /* *p == P + Q */
+        *q = *p - *q; /* *q == P + Q - Q = P */
+        *p = *p - *q; /* *p == P + Q - P = Q */
+/* Advance pointers towards each other */
+        p++;
+        q--;
+    }
+}
+
+```
+
+### C: Different Signature
+
+```c
+    int* reverse_range(int arr[], int arrSize, int from, int to) {
+        if (from < 0 || to >= arrSize || to < from)
+            return NULL;
+        for (int i = from; i < to; i++) {
+            int temp = arr[i];
+            arr[i] = arr[to];
+            arr[to] = temp;
+            to--;
+        }
+        return arr;
+    }
+```
+
+## Q5
+
+### A
+
+Start out with the binary representation of 20, 00010100. Then shift the bits to the right and toggle bit 31. Then left shift (multiply by 2) and you get 20.
+2147483668 and 2 are two numbers that give 20 when multiplied.
+Also works with 1073741829 and 4.
+
+### B
+
+The easiest way at first would seems like it would be to get the largest unsigned integer, divide it by 7 and add 3 to get the overflow to 20, getting back to multiplying and you get 7. The problem is that doesn't work. You get 17.
+The next thing to try is doubling the integer and adding 20 to get it to overflow twice. Thankfully `0x200000014` is cleanly divisible by 7.
+
+`200000014*7=20`
+
+### C
+
+```c
+    printf("$1%.27d spear%c%.0x %.7sion %o\n", 0, 104, 962029, "evacuate", 13023);
+```
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