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--- haas:spring2017:unix:projects:irt0 [2017/03/12 16:50] – created wedge
+++ haas:spring2017:unix:projects:irt0 [2017/03/12 17:28] (current) – [Process] wedge
@@ Line 40: / Line 40: @@
 <cli>
 lab46:~/src/unix/irt0$ ./irt0
   base 2  |  base 8  |  base10  |  base16
 ----------+----------+----------+----------
 |      000 |        0 |     0x00
@@ Line 67: / Line 67: @@
   * $3- display signed decimal (with the parameter "signed")
+Numerical arguments are to be given in decimal.
+If provided, they should adjust the script's output accordingly.
+Some additional constraints/assumptions you can make:
+  * octal values MUST have at least 1 leading zero; that is the standard convention for displaying numbers in that base (to help distinguish them from decimal)
+  * hexadecimal values start with a leading "0x" prefix, this is among the more common ways of showing a hex value; also, the "lettered" digits for this project must be **UPPERCASE**.
+  * the maximum upper limit you can implement for is 255 (base 10), or **0xFF** hexadecimal. This will keep your output tidy (you're welcome).
+====Only specifying starting value====
+In the event only the starting value is specified, assume a count of 16 (so display 16 values, starting at the starting value). Note that for binary and octal, all numbers should be displayed in a block, so if an additional place value comes into the picture, leading zeros must be visible on the preceding values.
+For example:
+<cli>
+lab46:~/src/unix/irt0$ ./irt0 12
+  base 2  |  base 8  |  base10  |  base16
+----------+----------+----------+----------
+|      014 |       12 |     0x0C
+|      015 |       13 |     0x0D
+|      016 |       14 |     0x0E
+|      017 |       15 |     0x0F
+|      020 |       16 |     0x10
+|      021 |       17 |     0x11
+|      022 |       18 |     0x12
+|      023 |       19 |     0x13
+|      024 |       20 |     0x14
+|      025 |       21 |     0x15
+|      026 |       22 |     0x16
+|      027 |       23 |     0x17
+|      030 |       24 |     0x18
+|      031 |       25 |     0x19
+|      032 |       26 |     0x1A
+|      033 |       27 |     0x1B
+lab46:~/src/unix/irt0$
+</cli>
+====Specifying starting and ending value====
+We can adjust the range displayed by specifying an ending value as well:
+<cli>
+lab46:~/src/unix/irt0$ ./irt0 37 42
+  base 2  |  base 8  |  base10  |  base16
+----------+----------+----------+----------
+|      045 |       37 |     0x25
+|      046 |       38 |     0x26
+|      047 |       39 |     0x27
+|      050 |       40 |     0x28
+|      051 |       41 |     0x29
+|      052 |       42 |     0x2A
+lab46:~/src/unix/irt0$
+</cli>
+With a specified starting/ending value pair, we can display as little as 1 value and (theoretically) as many as we want.
+====Specifying signed column====
+With the word "signed" given as the third parameter (ie starting and ending values are required), the following will occur:
+<cli>
+lab46:~/src/unix/irt0$ ./irt0 2 14 signed
+  base 2  |  base 8  |  base10  |  signed  |  base16
+----------+----------+----------+----------+----------
+|      002 |        2 |       +2 |     0x02
+|      003 |        3 |       +3 |     0x03
+|      004 |        4 |       +4 |     0x04
+|      005 |        5 |       +5 |     0x05
+|      006 |        6 |       +6 |     0x06
+|      007 |        7 |       +7 |     0x07
+|      010 |        8 |       -8 |     0x08
+|      011 |        9 |       -7 |     0x09
+|      012 |       10 |       -6 |     0x0A
+|      013 |       11 |       -5 |     0x0B
+|      014 |       12 |       -4 |     0x0C
+lab46:~/src/unix/irt0$
+</cli>
+Signed values are how the computer represents negative numbers. The convention in common use is to reference the most significant bit (the left-most): if it is a 1, it is considered negative, and 0, it is positive.
+The actual process of representing a number as a negative value is known as **two's complement**. In it, we invert the bits and add one.
+For instance, if we had 4-bit values and we wanted to display a 1 as a negative value:
+<code>
+   <-- value
+   <-- inversion of value's bits
+     +1   <-- adding 1
+   ====
+   <-- -1
+</code>
+=====Specifications=====
+Evaluation will be based on correctness of values as well as on formatting/spacing.
+You'll notice that everything lines up and is positioned similarly:
+  * each column exists within 8 characters of on-screen real estate, with one addition space padding the left and the right margins of the column.
+  * The values are right justified with each column, with all bases but decimal being exactly the same length (prepending leading zeroes if necessary)
+  * The dashes and vertical bars set up an ASCII art-like table pattern that helps make the data more readable.
+  * You are to manually print out no more than 2 consecutive spaces at a time in your output statements. If you need more, use one of the formatting tools to generate spaces for you.
+    * Obviously you'll need end results that occupy some sequence of spaces. The distinction I'm making is you're not to do stuff like: **echo "     $value"**
+    * I suggest getting cozy with the **printf(1)** tool
+  * The signed functionality is **optional**; I will consider its implementation for extra credit. Implemented or otherwise, however, your script should not generate any errors should a third argument in proper form be given.
+  * You need to check your arguments to ensure they are present and valid. Some examples:
+    * starting value is a valid (whole) number, and it is greater than or equal to 0
+    * ending value is a valid (whole) number, and it is:
+      * greater than or equal to the starting value, AND
+      * less than or equal to 255
+    * signed third argument is just that, the word, present or not present
+    * any invalid arguments (invalid number, NOT the word **signed** as an optional third argument), should result in an error message being generated.
 =====Submission=====
 By successfully performing this project, you should have a set of task#.cli files (one for each task). You will want to submit these, along with a **upf1steps** file.

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