Notes on binary shifting.

notes/.obsidian/plugins/obsidian-to-anki-plugin/data.json

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     "logic/truth-tables.md": "7892ceaa416c9a65acc79ca1e6ff778f",
     "logic/short-circuit.md": "26d300f407f14883022d0ef8dc4f7300",
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notes/_journal/2024-02-13.md

@@ -15,3 +15,4 @@ title: "2024-02-13"
 * Continued practicing One Summer's Day.
 * Read 혹부리 할아버지 (The Old Man with the Lump).
 * Begin adding notes/flashcards on `printf`. It's format specifier is used in enough places to warrant it.
+* Started playing Nier Automata.

notes/binary/index.md

@@ -1,5 +1,7 @@
 ---
 title: Binary
+TARGET DECK: Obsidian::STEM
+FILE TAGS: binary
 tags:
   - binary
 ---

notes/binary/shifts.md

@@ -156,6 +156,44 @@ Tags: c
 <!--ID: 1707854589813-->
 END%%
 
+In C, it is undefined behavior to shift by more than the width $w$ of an integral type. Typically though, only the last $w$ bits are considered in the computation. For example, given `int32_t x`, `(x << 32) = (x << 0)`.
+
+%%ANKI
+Basic
+According to the C standard, what is the result of shifting an `int32_t` value by `32`?
+Back: It is undefined behavior.
+Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
+Tags: c
+<!--ID: 1707873410765-->
+END%%
+
+%%ANKI
+Basic
+According to the C standard, what is the result of shifting an `int32_t` value by a negative value?
+Back: It is undefined behavior.
+Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
+Tags: c
+<!--ID: 1707873410773-->
+END%%
+
+%%ANKI
+Basic
+Ignoring UB, what *typically* happens when shifting an `int32_t` by `k ≥ 32` bits?
+Back: The shift value is interpreted as `k mod 32`.
+Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
+Tags: c
+<!--ID: 1707873410777-->
+END%%
+
+%%ANKI
+Basic
+How is $x \bmod 2^k$ equivalently written as a bit mask?
+Back: `x & (k - 1)`
+Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
+Tags: c
+<!--ID: 1707873410780-->
+END%%
+
 ## References
 
 * Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.