Initial commit.

explode.c

@@ -0,0 +1,201 @@
+#include <stdio.h>
+
+static unsigned char explode_token_base[4] = { 6, 10, 10, 18 };
+static unsigned char static_token_extra_bits[12] = { 1,  1,  1,  1,  2,  3,  3,  4,  4,  5,  7, 14 };
+
+unsigned char *src, *cmpr_data;
+unsigned int write_pos, src_size, src_end /*a4*/, token_run_len /*d2*/;
+int cmpr_pos /*a3*/;
+
+unsigned char token;
+
+unsigned short run_base_off_tbl[8];
+unsigned char run_extra_bits_tbl[12];
+
+static void copy_bytes(unsigned char *dst, unsigned char *src, int count){
+	for (int i = 0; i < count; i++){
+		dst[i] = src[i];
+	}
+}
+
+static unsigned short read_word(unsigned char *buf){
+	return ((buf[0] << 8) | buf[1]);
+}
+
+static unsigned int read_dword(unsigned char *buf){
+	return ((read_word(&buf[0]) << 16) | read_word(&buf[2]));
+}
+
+static void write_word(unsigned char *dst, unsigned short value){
+	dst[0] = (value >> 8) & 0xFF;
+	dst[1] = (value >> 0) & 0xFF;
+}
+
+static void write_dword(unsigned char *dst, unsigned int value){
+	write_word(&dst[0], (value >> 16) & 0xFFFF);
+	write_word(&dst[2], (value >> 0) & 0xFFFF);
+}
+
+unsigned int read_bits(unsigned char count){
+	unsigned int retn = 0;
+
+	for (int i = 0; i < count; i++){
+		char bit = (token >> 7);
+		token <<= 1;
+
+		if (!token){
+			token = (cmpr_data[cmpr_pos-1] << 1) | bit;
+			bit = (cmpr_data[--cmpr_pos] >> 7);
+		}
+
+		retn <<= 1;
+		retn |= bit;
+	}
+	return retn;
+}
+
+int check_imp(unsigned char *input){
+	unsigned int id, end_off, out_len;
+
+	if (!input){
+		return 0;
+	}
+
+	id = read_dword(&input[0]);
+	out_len = read_dword(&input[4]);
+	end_off = read_dword(&input[8]);
+
+	/* check for magic ID 'IMP!', or one of the other IDs used by Imploder
+	clones; ATN!, BDPI, CHFI, Dupa, EDAM, FLT!, M.H., PARA and RDC9 */
+	if (id != 0x494d5021 && id != 0x41544e21 && id != 0x42445049 && id != 0x43484649 && id != 0x44757061 &&
+			id != 0x4544414d && id != 0x464c5421 && id != 0x4d2e482e && id != 0x50415241 &&	id != 0x52444339){
+		return 0;
+	}
+
+	/* sanity checks */
+	return !((end_off & 1) || (end_off < 14) || ((end_off + 0x26) > out_len));
+}
+
+int explode(unsigned char *input){
+	if (!check_imp(input)){
+		return 0;
+	}
+
+	write_pos = 0, src_size = 0, src_end = 0 /*a4*/, token_run_len = 0 /*d2*/;
+	cmpr_pos = 0 /*a3*/;
+	token = 0;
+
+	src = input;
+	src_end = src_size = read_dword(&src[0x04]);
+	cmpr_data = &src[read_dword(&src[0x08])];
+	cmpr_pos = 0;
+
+	write_dword(&src[0x08], read_dword(&cmpr_data[0x00]));
+	write_dword(&src[0x04], read_dword(&cmpr_data[0x04]));
+	write_dword(&src[0x00], read_dword(&cmpr_data[0x08]));
+
+	token_run_len = read_dword(&cmpr_data[0x0C]);
+
+	if (!(cmpr_data[0x10] & 0x80)){
+		cmpr_pos--;
+	}
+
+	token /*d3*/ = cmpr_data[0x11];
+
+	for (int i = 0; i < 8; i++){
+		/*a1*/run_base_off_tbl[i] = read_word(&cmpr_data[0x12+i*2]);
+	}
+
+	copy_bytes(&run_extra_bits_tbl[0], &cmpr_data[0x22], 12);
+//int cnt = 0;
+	while (1){
+		for (int i = 0; (i < token_run_len) && (src_end > 0); i++){
+			src[--src_end] = cmpr_data[--cmpr_pos];
+		}
+
+		if (src_end == 0){
+			break;
+		}
+
+		unsigned int match_len, selector;
+
+		if (read_bits(1)){
+			if (read_bits(1)){
+				if (read_bits(1)){
+					if (read_bits(1)){
+						if (read_bits(1)){
+							match_len = cmpr_data[--cmpr_pos];
+							selector = 3;
+						}
+						else{
+							match_len = read_bits(3) + 6;
+							selector = 3;
+						}
+					}
+					else{
+						match_len = 5;
+						selector = 3;
+					}
+				}
+				else{
+					match_len = 4;
+					selector = 2;
+				}
+			}
+			else{
+				match_len = 3;
+				selector = 1;
+			}
+		}
+		else{
+			match_len = 2;
+			selector = 0;
+		}
+
+		if (read_bits(1)){
+			if (read_bits(1)){
+				token_run_len = read_bits(static_token_extra_bits[selector+8]) + explode_token_base[selector];
+			}
+			else{
+				token_run_len = read_bits(static_token_extra_bits[selector+4]) + 2;
+			}
+		}
+		else{
+			token_run_len = read_bits(static_token_extra_bits[selector]);
+		}
+
+		unsigned char *match;
+
+		if (read_bits(1)){
+			if (read_bits(1)){
+				match = &src[src_end + read_bits(run_extra_bits_tbl[8+selector]) + run_base_off_tbl[4+selector] + 1];
+			}
+			else{
+				match = &src[src_end + read_bits(run_extra_bits_tbl[4+selector]) + run_base_off_tbl[selector] + 1];
+			}
+		}
+		else{
+			match = &src[src_end + read_bits(run_extra_bits_tbl[selector]) + 1];
+		}
+
+		//printf("%06X-%06X\n", match_len, src_end); cnt++;
+
+		for (int i = 0; (i < match_len) && (src_end > 0); i++){
+			src[--src_end] = *--match;
+		}
+	}
+
+	return src_size;
+}
+
+int imploded_size(unsigned char *input){
+	if(!check_imp(input)) return 0;
+
+	return read_dword(&input[8]) + 0x32;
+}
+
+int exploded_size(unsigned char *input){
+	if(!check_imp(input)) return 0;
+
+	return read_dword(&input[4]);
+}

explode.h

@@ -0,0 +1,4 @@
+int explode(unsigned char *input);
+int imploded_size(unsigned char *input);
+int check_imp(unsigned char *input);
+int exploded_size(unsigned char *input);