diff --git a/.gitignore b/.gitignore
index 5e7833aef76bb4f56b5e7c1e6513f374d3581dee..eaa40e159992946435667dc472f4adfae53b846c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,4 @@
myzip0
myunzip0
-inflate
-huffman
\ No newline at end of file
+./inflate
+huffman
diff --git a/src/inflate/inflate.c b/src/inflate/inflate.c
new file mode 100644
index 0000000000000000000000000000000000000000..955f602aad13c8e4d8168b45945cf84d960209f9
--- /dev/null
+++ b/src/inflate/inflate.c
@@ -0,0 +1,449 @@
+#include <stdio.h>
+#include <assert.h>
+#include <string.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+#include <inflate.h>
+
+/* Types of huffman codes */
+#define FIXED 1
+#define DYNAMIC 2
+
+/* Dummy value for min_codes in huffman_t structs */
+#define NO_CODE -1
+
+/*
+ * Constants for FIXED code type
+ */
+
+/* Alphabet for codes of length 7, 8, and 9, in order
+ * Not really intended for use; use HUFFMAN_FIXED instead.
+ */
+
+int _FIXED_7[24] = {256, 257, 258, 259, 260, 261, 262, 263, 264, 265, 266, 267, 268,
+ 269, 270, 271, 272, 273, 274, 275, 276, 277, 278, 279};
+
+int _FIXED_8[152] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
+ 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30,
+ 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44,
+ 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58,
+ 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72,
+ 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86,
+ 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100,
+ 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111,
+ 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122,
+ 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133,
+ 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 280,
+ 281, 282, 283, 284, 285, 286, 287};
+
+int _FIXED_9[112] = {144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154,
+ 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165,
+ 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176,
+ 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187,
+ 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198,
+ 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209,
+ 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220,
+ 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231,
+ 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242,
+ 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253,
+ 254, 255
+};
+
+/* Note that we only have codes of length 7, 8, 9 */
+huffman_t HUFFMAN_FIXED = {
+ .bl_counts = {0, 0, 0, 0, 0, 0, 0, 24, 152, 112, 0, 0, 0, 0, 0},
+
+ .alphabet = {NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+ _FIXED_7, _FIXED_8, _FIXED_9,
+ NULL, NULL, NULL, NULL, NULL},
+
+ .min_codes = {NO_CODE, NO_CODE, NO_CODE, NO_CODE, NO_CODE, NO_CODE, NO_CODE,
+ 0, 48, 192, 400,
+ NO_CODE, NO_CODE, NO_CODE, NO_CODE, NO_CODE}
+};
+
+
+/* Number of characters in the code-length alphabet */
+#define N_CL_ALPHABET 19
+
+int CL_ALPHABET[N_CL_ALPHABET] = {
+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18
+};
+
+
+/* Number of characters in the distance alphabet */
+#define N_DISTS 30
+
+int DIST_ALPHABET[N_DISTS] = {
+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
+ 21, 22, 23, 24, 25, 26, 27, 28, 29
+};
+
+huffman_t HUFFMAN_FIXED_DISTS = {
+ .bl_counts = {0, 0, 0, 0, 0, 30, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+
+ .alphabet = {NULL, NULL, NULL, NULL, NULL, DIST_ALPHABET, NULL, NULL,
+ NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL},
+
+ .min_codes = {NO_CODE, NO_CODE, NO_CODE, NO_CODE, NO_CODE, 0,
+ NO_CODE, NO_CODE, NO_CODE, NO_CODE, NO_CODE, NO_CODE,
+ NO_CODE, NO_CODE, NO_CODE, NO_CODE}
+};
+
+/* Conversion tables for lengths
+ * To index into lengths, use (value_read - LENGTH_OFFSET)
+ * We may have to read additional bits; check LEN_ADDITIONAL for how many
+ */
+#define LENGTH_OFFSET 257
+int LEN_TABLE[29] = {
+ 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, 35, 43, 51,
+ 59, 67, 83, 99, 115, 131, 163, 195, 227, 258
+};
+
+int LEN_ADDITIONAL[29] = {
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ 1, 1, 1, 1, 2, 2, 2, 2,
+ 3, 3, 3, 3, 4, 4, 4, 4,
+ 5, 5, 5, 5, 0
+};
+
+/* Conversion tables for distance codes
+ * This can be indexed into directly with the distance code.
+ * Again, we may have to read additional bits to get the distance.
+ */
+int DIST_TABLE[30] = {
+ 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 257, 385, 513,
+ 769, 1025, 1537, 2049, 3073, 4097, 6145, 8193, 12289, 16385, 24577
+};
+int DIST_ADDITIONAL[30] = {
+ 0, 0, 0, 0, 1, 1, 2, 2,
+ 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8,
+ 9, 9, 10, 10, 11, 11, 12, 12, 13, 13
+};
+
+/*
+ * Constants for DYNAMIC code type
+ */
+
+/* Number of characters in the literal-length alphabet */
+#define N_LITERALS 286
+
+int LITERAL_ALPHABET[N_LITERALS] = {
+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
+ 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38,
+ 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56,
+ 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74,
+ 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92,
+ 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108,
+ 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123,
+ 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138,
+ 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153,
+ 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168,
+ 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183,
+ 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198,
+ 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213,
+ 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228,
+ 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243,
+ 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255, 256, 257, 258,
+ 259, 260, 261, 262, 263, 264, 265, 266, 267, 268, 269, 270, 271, 272, 273,
+ 274, 275, 276, 277, 278, 279, 280, 281, 282, 283, 284, 285
+};
+
+/* After the dynamic block header, a sequence of lengths
+ * occurs; the lengths correspond to characters in the
+ * code-length alphabet in this order.
+ */
+int CL_ORDER[N_CL_ALPHABET] = {
+ 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15
+};
+
+/* Keep track of the bit we are at.
+ * DO NOT MODIFY ANYWHERE EXCEPT get_next_bit */
+int _CUR_BIT = 0;
+
+/* Resets _CUR_BIT to 0. */
+void reset_pos() {
+ _CUR_BIT = 0;
+}
+
+int get_next_bit(char *buf) {
+ int buf_pos = _CUR_BIT / 8;
+ int pos = _CUR_BIT - 8 * buf_pos;
+
+ char byte = buf[buf_pos];
+ char mask = 1 << pos;
+
+ _CUR_BIT += 1;
+
+ return ((byte & mask) != 0);
+}
+
+int get_n_bits(char *buf, int n, bool reverse) {
+ int res = 0;
+ for (int i = 0; i < n; i++) {
+ if (!reverse) {
+ res += get_next_bit(buf) << (n - i - 1);
+ } else {
+ res += get_next_bit(buf) << i;
+ }
+ }
+ return res;
+}
+
+int read_chunk(char *buf, huffman_t hf) {
+ int code = 0;
+ /* There should be no codes of length 0, so we can start at 1 */
+ for (int i = 1; i < MAX_LENGTH + 1; i++) {
+ /* We haven't matched up to this point; shift left, and read another bit */
+ code <<= 1;
+ code += get_next_bit(buf);
+ /* Do we have codes of length i? */
+ if (hf.alphabet[i] != NULL) {
+ /* Index into hf.alphabet[i], i.e. values for codes of length i */
+ int idx = (code - hf.min_codes[i]);
+ /* If this is a valid index, then we have a match of length i */
+ if (idx < hf.bl_counts[i]) {
+ return hf.alphabet[i][idx];
+ }
+ }
+ }
+
+ /* Something has gone wrong if we reach here */
+ return -1;
+}
+
+huffman_t *make_huffman(int *lens, int *alphabet, int n_symbols) {
+ huffman_t *hf = (huffman_t *) malloc(sizeof(huffman_t));
+ /* Initialize fields */
+ for (int i = 0; i < MAX_LENGTH + 1; i++) {
+ hf->bl_counts[i] = 0;
+ hf->alphabet[i] = NULL;
+ hf->min_codes[i] = NO_CODE;
+ }
+
+ /* Update bl_counts with the lens */
+ for (int i = 0; i < n_symbols; i++) {
+ int len = lens[i];
+ if (len != 0) {
+ hf->bl_counts[len] += 1;
+ }
+ }
+
+ /*
+ * Construct min_codes, the value of the smallest code for each
+ * code length
+ */
+ int code = 0;
+ for (int i = 1; i < MAX_LENGTH + 1; i++) {
+ code = (code + hf->bl_counts[i - 1]) << 1;
+ if (hf->bl_counts[i] != 0) hf->min_codes[i] = code;
+ }
+
+ /*
+ * Start assigning codes to alphabet characters.
+ */
+ for (int len = 0; len < MAX_LENGTH + 1; len++) {
+ if (hf->bl_counts[len] != 0) {
+ int *symbols = (int *) malloc(hf->bl_counts[len] * sizeof(int));
+ int cur = 0;
+
+ for (int sym = 0; sym < n_symbols; sym++) {
+ if (lens[sym] == len) {
+ symbols[cur] = sym;
+ cur += 1;
+ }
+ }
+ hf->alphabet[len] = symbols;
+ }
+ }
+
+ return hf;
+}
+
+void destroy_huffman(huffman_t *hf) {
+ for (int i = 0; i < MAX_LENGTH + 1; i++) {
+ if (hf->alphabet[i] != NULL) free(hf->alphabet[i]);
+ }
+ free(hf);
+}
+
+int *read_lens(char *buf, huffman_t *hf_codes, int num_symbols, int num_codes) {
+ int *lens = (int *) malloc(num_symbols * sizeof(int));
+ for (int i = 0; i < num_symbols; i++) lens[i] = 0;
+
+ int cur_lit = 0;
+
+ while (cur_lit < num_codes) {
+ int len = read_chunk(buf, *hf_codes);
+ if (len <= 15) {
+ lens[cur_lit] = len;
+ cur_lit += 1;
+ } else if (len == 16) {
+ int rep = get_n_bits(buf, 2, true) + 3;
+ int prev = lens[cur_lit - 1];
+
+ for (int j = 0; j < rep; j++) {
+ lens[cur_lit] = prev;
+ cur_lit += 1;
+ }
+ } else if (len == 17) {
+ int rep = get_n_bits(buf, 3, true) + 3;
+ for (int j = 0; j < rep; j++) {
+ lens[cur_lit] = 0;
+ cur_lit += 1;
+ }
+ } else if (len == 18) {
+ int rep = get_n_bits(buf, 7, true) + 11;
+ for (int j = 0; j < rep; j++) {
+ lens[cur_lit] = 0;
+ cur_lit += 1;
+ }
+ } else {
+ fprintf(stderr, "error: invalid length");
+ exit(1);
+ }
+ }
+ return lens;
+}
+
+void read_block(char *buf, FILE *out) {
+ /* First bit is the BFINAL flag */
+
+ bool bfinal = get_next_bit(buf);
+
+ /* Next two bits are BTYPE */
+ int btype = get_n_bits(buf, 2, true);
+
+ /* By default, use fixed mapping */
+ huffman_t *hf = &HUFFMAN_FIXED;
+ huffman_t *hf_dist = &HUFFMAN_FIXED_DISTS;
+
+ if (btype == DYNAMIC) {
+ /* Read dynamic block header */
+ int hlit = get_n_bits(buf, 5, true);
+ int hdist = get_n_bits(buf, 5, true);
+ int hclen = get_n_bits(buf, 4, true);
+
+ /* Read in the code lengths for the code-length alphabet */
+ int *lens_cl = (int *) malloc(N_CL_ALPHABET * sizeof(int));
+ for (int i = 0; i < N_CL_ALPHABET; i++) lens_cl[i] = 0;
+
+ for (int i = 0; i < hclen + 4; i++) {
+ int len = get_n_bits(buf, 3, true);
+ int cl = CL_ORDER[i];
+ lens_cl[cl] = len;
+ }
+
+ huffman_t *hf_codes = make_huffman(lens_cl, CL_ALPHABET, N_CL_ALPHABET);
+
+ /* Now read in the code lengths for the literal alphabet */
+ int *lens_lit = read_lens(buf, hf_codes, N_LITERALS, hlit + 257);
+
+ /* Huffman mapping for the length-literal alphabet */
+ huffman_t *hf_lit = make_huffman(lens_lit, LITERAL_ALPHABET, N_LITERALS);
+
+ /* Read in the lengths for the distance alphabet */
+ int *lens_dist = read_lens(buf, hf_codes, N_DISTS, hdist + 1);
+
+ /* Huffman mapping for the distance code alphabet */
+ huffman_t *hf_dist_new = make_huffman(lens_dist, DIST_ALPHABET, N_DISTS);
+
+ /* Cleanup */
+ destroy_huffman(hf_codes);
+ free(lens_cl);
+ free(lens_lit);
+ free(lens_dist);
+
+ hf = hf_lit;
+ hf_dist = hf_dist_new;
+
+ } else if (btype != FIXED) {
+ fprintf(stderr, "error: unrecognized btype\n");
+ exit(1);
+ }
+
+ /* Read to decode when we reach this point. */
+ int chunk_val;
+
+ do
+ {
+ /* Match a huffman code */
+ chunk_val = read_chunk(buf, *hf);
+
+ /* Literal, just write to output buffer */
+ if (chunk_val < 256) {
+ fwrite(&chunk_val, 1, sizeof(char), out);
+ /* We read a length */
+ } else if (chunk_val > 256) {
+ int length = LEN_TABLE[chunk_val - LENGTH_OFFSET];
+ int addit_len = LEN_ADDITIONAL[chunk_val - LENGTH_OFFSET];
+ length += get_n_bits(buf, addit_len, true);
+
+ /* Read in the distance code */
+ int dist_code = read_chunk(buf, *hf_dist);
+ assert(dist_code != -1);
+ int dist = DIST_TABLE[dist_code];
+ int addit_dist = DIST_ADDITIONAL[dist_code];
+ dist += get_n_bits(buf, addit_dist, true);
+ for (int i = 0; i < length; i++) {
+ fseek(out, -dist, SEEK_CUR);
+ int val = fgetc(out);
+ fseek(out, 0, SEEK_END);
+ fwrite(&val, 1, sizeof(char), out);
+ }
+ }
+ }
+ while (chunk_val != 256);
+
+ /* Skip over filler at the end of the block */
+ while (_CUR_BIT % 8 != 0) {
+ _CUR_BIT += 1;
+ }
+
+ if (btype == DYNAMIC) {
+ destroy_huffman(hf);
+ destroy_huffman(hf_dist);
+ }
+}
+
+void truncate_suffix(char *fname) {
+ char *dot = strrchr(fname, '.');
+
+ const char *suffix = ".deflate";
+
+ for (int i = 0; i < 8; i++) {
+ if (dot == NULL || *(dot + i) != suffix[i]) {
+ fprintf(stderr, "error: must be a .deflate file");
+ exit(1);
+ }
+ }
+ *dot = '\0';
+}
+
+void inflate(FILE *fp, char *fname) {
+ truncate_suffix(fname);
+
+ /* Create output file */
+ FILE *out = fopen(fname, "wb+");
+
+ /* Read the file into a buffer */
+ fseek(fp, 0, SEEK_END);
+ long size = ftell(fp);
+ rewind(fp);
+ char *buf = (char *) malloc(size);
+ if (!buf) {
+ fprintf(stderr, "error: memory error\n");
+ exit(1);
+ }
+ fread(buf, 1, size, fp);
+
+ while (_CUR_BIT < 8 * size) {
+ read_block(buf, out);
+ }
+
+ fclose(out);
+ free(buf);
+}
+
diff --git a/src/inflate/main.c b/src/inflate/main.c
new file mode 100644
index 0000000000000000000000000000000000000000..852bd9fecbc63081c08f3dbfe1cc2ce11188d1db
--- /dev/null
+++ b/src/inflate/main.c
@@ -0,0 +1,25 @@
+#include <stdio.h>
+#include <stdbool.h>
+
+#include <inflate.h>
+
+int main(int argc, char *argv[]) {
+ if (argc != 2) {
+ fprintf(stderr, "usage: inflate [file]\n");
+ return 1;
+ }
+
+ char *fname = argv[1];
+
+ FILE *fp = fopen(fname, "rb");
+
+ if (!fp) {
+ fprintf(stderr, "error: file not found\n");
+ return 1;
+ }
+
+ inflate(fp, fname);
+
+ fclose(fp);
+ return 0;
+}