Add huffman and example file

.gitignore

 myzip0
 myunzip0
+inflate
+huffman
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Makefile

-all : myzip0 myunzip0
+all : myzip0 myunzip0 huffman
 
 myzip0 : myzip0.c
 	cc myzip0.c -o myzip0
 
 myunzip0 : myunzip0.c
-	cc myunzip0.c -o myunzip0
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+	cc myunzip0.c -o myunzip0
+
+huffman : huffman.c
+	cc huffman.c -o huffman
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example.bin

+"3DUfw
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huffman.c

+#include <stdlib.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <string.h>
+#include <assert.h>
+
+/* A struct for writing to files as
+   streams of individual bits */
+
+typedef struct __bit_writer
+{
+    FILE *file;
+    uint8_t byte;
+    int mod;
+} bit_writer;
+
+bit_writer *bit_writer_init(FILE *file)
+{
+    bit_writer *bw = malloc(sizeof(bit_writer));
+    assert(bw);
+    bw->file = file;
+    bw->byte = 0;
+    bw->mod = 0;
+    return bw;
+}
+
+void bit_writer_free(bit_writer *bw)
+{
+    free(bw);
+}
+
+void bit_writer_write_bit(bit_writer *bw, bool bit)
+{
+    bw->byte |= (bit > 0) << (bw->mod++);
+
+    if (bw->mod == 8)
+    {
+        fwrite(&bw->byte, 1, 1, bw->file);
+        bw->byte = 0;
+        bw->mod = 0;
+    }
+}
+
+void bit_writer_flush(bit_writer *bw)
+{
+    while (bw->mod != 0) bit_writer_write_bit(bw, 0);
+}
+
+void write_byte(bit_writer *bw, uint8_t byte)
+{
+
+    if (byte <= 143) /* 8 bit encoding */
+    {
+        uint32_t to_encode = 0x30 + (uint32_t) byte;
+        for (int b = 8 - 1; b >= 0; b--)
+            bit_writer_write_bit(bw, to_encode & (1 << b));
+    } else /* 9 bit encoding */
+    {
+        uint32_t to_encode = 0x100 + (uint32_t) byte;
+        for (int b = 9 - 1; b >= 0; b--)
+        {
+            // bool to_write = () != 0;
+            // printf("Writing %d\n", to_write);
+            bit_writer_write_bit(bw, to_encode & (1 << b));
+        }
+    }
+}
+
+int main(int argc, char *argv[])
+{
+    if (argc != 2)
+    {
+        printf("Usage: %s <input file>\n", argv[0]);
+        exit(1);
+    }
+
+    char *input_file_name = argv[1];
+    char *output_file_name = malloc(sizeof(char) * 
+        (strlen(input_file_name) + strlen(".deflate") + 1));
+    sprintf(output_file_name, "%s.deflate", input_file_name);
+
+    FILE *input_file = fopen(input_file_name, "r");
+    FILE *output_file = fopen(output_file_name, "w");
+    free(output_file_name);
+    bit_writer *bw = bit_writer_init(output_file);
+
+
+
+    bit_writer_write_bit(bw, 1); /* BFINAL */
+    
+    bit_writer_write_bit(bw, 1); /* BTYPE */
+    bit_writer_write_bit(bw, 0);
+
+    // write_byte(bw, 144);
+
+    char c;
+    while (fread(&c, 1, 1, input_file))
+    {
+        // printf("Writing %d\n", (int) c);
+        write_byte(bw, c);
+    }
+
+    for (int i = 0; i < 7; i++)
+        bit_writer_write_bit(bw, 0);
+
+    bit_writer_flush(bw);
+    bit_writer_free(bw);
+    fclose(output_file);
+    fclose(input_file);
+
+
+
+    return 0;
+}
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