diff --git a/tools/CMakeLists.txt b/tools/CMakeLists.txt
index 596babbf..558c7d83 100644
--- a/tools/CMakeLists.txt
+++ b/tools/CMakeLists.txt
@@ -1,5 +1,5 @@
 add_executable(bitread bitread.cc)
-target_link_libraries(bitread gflags absl::strings)
+target_link_libraries(bitread absl::optional absl::strings gflags libprjxray)
 
 add_executable(segmatch segmatch.cc)
 target_link_libraries(segmatch gflags absl::strings)
diff --git a/tools/bitread.cc b/tools/bitread.cc
index bdbb70a9..3b81b57c 100644
--- a/tools/bitread.cc
+++ b/tools/bitread.cc
@@ -1,25 +1,28 @@
 #include <stdio.h>
 #include <stdint.h>
 #include <string.h>
-#include <unistd.h>
-#include <vector>
+
+#include <iostream>
 #include <string>
-#include <map>
 #include <set>
+#include <vector>
 
 #include <absl/strings/numbers.h>
 #include <absl/strings/str_cat.h>
 #include <absl/strings/str_split.h>
+#include <absl/types/optional.h>
 #include <gflags/gflags.h>
+#include <prjxray/memory_mapped_file.h>
+#include <prjxray/xilinx/xc7series/bitstream_reader.h>
+#include <prjxray/xilinx/xc7series/configuration.h>
+#include <prjxray/xilinx/xc7series/part.h>
 
 DEFINE_bool(c, false, "output '*' for repeating patterns");
 DEFINE_bool(C, false, "do not ignore the checksum in each frame");
 DEFINE_int32(f, -1, "only dump the specified frame (might be used more than once)");
 DEFINE_string(F, "", "<first_frame_address>:<last_frame_address> only dump frame in the specified range");
-DEFINE_bool(m, false, "print commands in config stream");
 DEFINE_string(o, "", "write machine-readable output file with config frames");
 DEFINE_bool(p, false, "output a binary netpgm image");
-DEFINE_bool(r, false, "only decode top-level .bit file format framing");
 DEFINE_bool(x, false, "use format 'bit_%%08x_%%03d_%%02d_t%%d_h%%d_r%%d_c%%d_m%%d'\n"
 		      "The fields have the following meaning:\n"
 		      "  - complete 32 bit hex frame id\n"
@@ -32,239 +35,26 @@ DEFINE_bool(x, false, "use format 'bit_%%08x_%%03d_%%02d_t%%d_h%%d_r%%d_c%%d_m%%
 		      "  - decoded minor address from frame id\n");
 DEFINE_bool(y, false, "use format 'bit_%%08x_%%03d_%%02d'");
 DEFINE_bool(z, false, "skip zero frames (frames with all bits cleared) in o");
+DEFINE_string(part_file, "", "YAML file describing a Xilinx 7-Series part");
+
+namespace xc7series = prjxray::xilinx::xc7series;
 
 std::set<uint32_t> frames;
-
 uint32_t frame_range_begin = 0, frame_range_end = 0;
 
-std::vector<uint8_t> bitdata;
-int cursor;
-
-std::string header_a, header_b, header_c, header_d;
-std::vector<uint32_t> configdata;
-
-uint32_t frameptr = 0;
-std::map<uint32_t, std::vector<uint32_t>> configframes;
-std::set<uint32_t> configframes_autoincr;
-
 std::vector<uint32_t> zero_frame(101);
-std::vector<uint32_t> framebuffer;
 
-uint32_t selbits(uint32_t value, int msb, int lsb)
-{
-	return (value >> lsb) & ((1 << (msb-lsb+1)) - 1);
-}
-
-void print_hexblock(int len)
-{
-	if (!FLAGS_r) {
-		cursor += len;
-		return;
-	}
-
-	int index = 0;
-	std::vector<uint8_t> lastbuf;
-	bool in_continue = false;
-
-	while (len > 0)
-	{
-		char asciibuf[17];
-		asciibuf[16] = 0;
-
-		if (len > 16 && FLAGS_c) {
-			std::vector<uint8_t> thisbuf(bitdata.begin()+cursor, bitdata.begin()+cursor+16);
-			if (lastbuf == thisbuf) {
-				if (!in_continue)
-					printf("*\n");
-				in_continue = true;
-				cursor += 16;
-				index += 16;
-				len -= 16;
-				continue;
-			}
-			lastbuf.swap(thisbuf);
-			in_continue = false;
-		}
-
-		printf("%06x: ", index);
-		index += 16;
-
-		for (int i = 0; i < 16; i++) {
-			if (i % 4 == 0)
-				printf(" ");
-			if (len > 0) {
-				printf("%02x ", bitdata.at(cursor));
-				asciibuf[i] = (32 <= bitdata.at(cursor) && bitdata.at(cursor) < 128) ? bitdata.at(cursor) : '.';
-				cursor++, len--;
-			} else {
-				printf("   ");
-				asciibuf[i] = ' ';
-			}
-		}
-
-		printf(" |%s|\n", asciibuf);
-	}
-}
-
-void print_pkt_len2()
-{
-	int len = (bitdata.at(cursor) << 8) + bitdata.at(cursor+1);
-
-	if (FLAGS_r)
-		printf("\nPkt at byte %d with length %d:\n", cursor, len);
-	cursor += 2;
-
-	print_hexblock(len);
-}
-
-void print_pkt_key_len2()
-{
-	int key = bitdata.at(cursor);
-	int len = (bitdata.at(cursor+1) << 8) + bitdata.at(cursor+2);
-
-	if (FLAGS_r)
-		printf("\nPkt '%c' at byte %d with length %d:\n", key, cursor, len);
-	cursor += 3;
-
-	print_hexblock(len);
-}
-
-void print_pkt_key_len4()
-{
-	int key = bitdata.at(cursor);
-	int len = (bitdata.at(cursor+1) << 24) + (bitdata.at(cursor+2) << 16) + (bitdata.at(cursor+3) << 8) + bitdata.at(cursor+4);
-
-	if (FLAGS_r)
-		printf("\nPkt '%c' at byte %d with length %d:\n", key, cursor, len);
-	cursor += 5;
-
-	for (int i = 0; i < len; i+= 4)
-		configdata.push_back((bitdata.at(cursor+i) << 24) + (bitdata.at(cursor+i+1) << 16) +
-				(bitdata.at(cursor+i+2) << 8) + bitdata.at(cursor+i+3));
-
-	print_hexblock(len);
-}
-
-#define REG_CRC      0
-#define REG_FAR      1
-#define REG_FDRI     2
-#define REG_FDRO     3
-#define REG_CMD      4
-#define REG_CTL0     5
-#define REG_MASK     6
-#define REG_STAT     7
-#define REG_LOUT     8
-#define REG_COR0     9
-#define REG_MFWR    10
-#define REG_CBC     11
-#define REG_IDCODE  12
-#define REG_AXSS    13
-#define REG_COR1    14
-#define REG_WBSTAR  16
-#define REG_TIMER   17
-#define REG_CRCSET  19
-#define REG_BOOTSTS 22
-#define REG_CTL1    24
-#define REG_BSPI    31
-
-const char *regname(int addr)
-{
-	switch (addr)
-	{
-	case REG_CRC:     return "CRC";
-	case REG_FAR:     return "FAR";
-	case REG_FDRI:    return "FDRI";
-	case REG_FDRO:    return "FDRO";
-	case REG_CMD:     return "CMD";
-	case REG_CTL0:    return "CTL0";
-	case REG_MASK:    return "MASK";
-	case REG_STAT:    return "STAT";
-	case REG_LOUT:    return "LOUT";
-	case REG_COR0:    return "COR0";
-	case REG_MFWR:    return "MFWR";
-	case REG_CBC:     return "CBC";
-	case REG_IDCODE:  return "IDCODE";
-	case REG_AXSS:    return "AXSS";
-	case REG_COR1:    return "COR1";
-	case REG_WBSTAR:  return "WBSTAR";
-	case REG_TIMER:   return "TIMER";
-	case REG_CRCSET:  return "CRCSET";
-	case REG_BOOTSTS: return "BOOTSTS";
-	case REG_CTL1:    return "CTL1";
-	case REG_BSPI:    return "BSPI";
-	default:          return "UNKOWN";
-	}
-}
-
-void start_write(int regaddr, bool /* type2 */)
-{
-	if (regaddr == REG_FDRI)
-		framebuffer.clear();
-}
-
-void handle_write(int regaddr, uint32_t data, bool type2)
-{
-	if (regaddr == REG_FAR) {
-		frameptr = data;
-		configframes[frameptr] = framebuffer;
-		configframes_autoincr.erase(frameptr);
-	}
-
-	if (regaddr == REG_FDRI) {
-		if (type2) {
-			if (configframes[frameptr].size() == 101) {
-				configframes[++frameptr].clear();
-				configframes_autoincr.insert(frameptr);
-			}
-			configframes[frameptr].push_back(data);
-		} else {
-			if (framebuffer.size() >= 101) {
-				printf("Framebuffer overflow!\n");
-				exit(1);
-			}
-			framebuffer.push_back(data);
-		}
-	}
-}
-
-class frameid
-{
-	uint32_t value;
-
-public:
-	frameid(uint32_t v) : value(v) { }
-
-	uint32_t get_value() const {
-		return value;
-	}
-
-	int get_type() const {
-		return selbits(value, 25, 23);
-	}
-
-	int get_topflag() const {
-		return selbits(value, 22, 22);
-	}
-
-	int get_rowaddr() const {
-		return selbits(value, 21, 17);
-	}
-
-	int get_coladdr() const {
-		return selbits(value, 16, 7);
-	}
-
-	int get_minor() const {
-		return selbits(value, 6, 0);
-	}
-};
-
-int main(int argc, char **argv)
-{
+int main(int argc, char **argv) {
 	gflags::SetUsageMessage(
 			absl::StrCat("Usage: ", argv[0], " [options] [bitfile]"));
 	gflags::ParseCommandLineFlags(&argc, &argv, true);
 
+	auto part = xc7series::Part::FromFile(FLAGS_part_file);
+	if (!part) {
+		std::cerr << "Part file not found or invalid" << std::endl;
+		return 1;
+	}
+
 	if (FLAGS_f >= 0) {
 		frames.insert(FLAGS_f);
 	}
@@ -275,315 +65,161 @@ int main(int argc, char **argv)
 		frame_range_end = strtol(p.second.c_str(), nullptr, 0) + 1;
 	}
 
+	absl::optional<xc7series::BitstreamReader> reader;
 	if (argc == 2) {
-		FILE *f = fopen(argv[1], "rb");
-		if (f == nullptr) {
-			printf("Can't open input file '%s' for reading!\n", argv[1]);
+		auto in_file_name = argv[1];
+		auto in_file = prjxray::MemoryMappedFile::InitWithFile(in_file_name);
+		if (!in_file) {
+			std::cerr << "Can't open input file '" << in_file_name
+				  << "' for reading!" << std::endl;
 			return 1;
 		}
-		while (1) {
-			int c = fgetc(f);
-			if (c == EOF) break;
-			bitdata.push_back(c);
-		}
-		fclose(f);
+
+		std::cout << "Bitstream size: " << in_file->size() << " bytes"
+	    		  << std::endl;
+
+		auto in_bytes = absl::Span<uint8_t>(
+				static_cast<uint8_t*>(in_file->data()),
+				in_file->size());
+		reader = xc7series::BitstreamReader::InitWithBytes(in_bytes);
 	} else {
+		std::vector<uint8_t> bitdata;
 		while (1) {
 			int c = getchar();
 			if (c == EOF) break;
 			bitdata.push_back(c);
 		}
+
+		std::cout << "Bitstream size: " << bitdata.size() << " bytes"
+	    		  << std::endl;
+
+		reader = xc7series::BitstreamReader::InitWithBytes(bitdata);
 	}
 
-	printf("Bitstream size: %d bytes\n", int(bitdata.size()));
-
-	cursor = 0;
-	while (cursor < int(bitdata.size()))
-	{
-		if (bitdata.at(cursor) == 0x00) {
-			header_a = (const char*)&bitdata.at(cursor+2);
-			print_pkt_len2();
-			continue;
-		}
-
-		if (bitdata.at(cursor) == 0x62) {
-			header_b = (const char*)&bitdata.at(cursor+3);
-			print_pkt_key_len2();
-			continue;
-		}
-
-		if (bitdata.at(cursor) == 0x63) {
-			header_c = (const char*)&bitdata.at(cursor+3);
-			print_pkt_key_len2();
-			continue;
-		}
-
-		if (bitdata.at(cursor) == 0x64) {
-			header_d = (const char*)&bitdata.at(cursor+3);
-			print_pkt_key_len2();
-			continue;
-		}
-
-		if (bitdata.at(cursor) == 0x65) {
-			print_pkt_key_len4();
-			continue;
-		}
-
-		printf("Top-level framing error at byte %d.\n", cursor);
+	if (!reader) {
+		std::cerr << "Bitstream does not appear to be a Xilinx "
+			  << "7-series bitstream!" << std::endl;
 		return 1;
 	}
 
-	if (!FLAGS_r)
+	std::cout << "Config size: " << reader->words().size()
+	   	  << " words" << std::endl;
+
+	auto config = xc7series::Configuration::InitWithPackets(*part, *reader);
+	if (!config) {
+		std::cerr << "Bitstream does not appear to be for this part"
+			  << std::endl;
+		return 1;
+	}
+
+	std::cout << "Number of configuration frames: "
+		  << config->frames().size() << std::endl;
+
+	FILE *f = stdout;
+
+	if (!FLAGS_o.empty())
 	{
-		printf("Header A: %s\n", header_a.c_str());
-		printf("Header B: %s\n", header_b.c_str());
-		printf("Header C: %s\n", header_c.c_str());
-		printf("Header D: %s\n", header_d.c_str());
-		printf("Config size: %d words\n", int(configdata.size()));
+		f = fopen(FLAGS_o.c_str(), "w");
 
-		cursor = 0;
-		while (cursor < int(configdata.size()))
-			if (configdata.at(cursor++) == 0xAA995566)
-				break;
-
-		printf("Skipped %d padding/header words.\n", cursor);
-
-		int current_write_reg = -1;
-
-		while (cursor < int(configdata.size()))
-		{
-			uint32_t cmd = configdata.at(cursor);
-			int cmd_header = selbits(cmd, 31, 29);
-
-			// Type 1 Packet
-			if (cmd_header == 1)
-			{
-				int opcode = selbits(cmd, 28, 27);
-				int regaddr = selbits(cmd, 26, 13);
-				int reserved = selbits(cmd, 12, 11);
-				int wcount = selbits(cmd, 10, 0);
-
-				if (reserved != 0 || regaddr > 31)
-					goto cmderror;
-
-				if (opcode == 0) {
-					if (FLAGS_m) {
-						printf("%8d: 0x%08x NOP\n", cursor, configdata.at(cursor));
-						if (FLAGS_c && cmd == 0x20000000 && cursor+1 < int(configdata.size()) && cmd == configdata.at(cursor+1)) {
-							while (cursor+1 < int(configdata.size()) && cmd == configdata.at(cursor+1)) cursor++;
-							printf("*\n");
-						}
-					}
-					goto handle_type1_payload;
-				}
-
-				if (opcode == 1) {
-					if (FLAGS_m)
-						printf("%8d: 0x%08x Read %s register (%d)\n", cursor, configdata.at(cursor), regname(regaddr), regaddr);
-					goto handle_type1_payload;
-				}
-
-				if (opcode == 2) {
-					if (FLAGS_m)
-						printf("%8d: 0x%08x Write %s register (%d)\n", cursor, configdata.at(cursor), regname(regaddr), regaddr);
-					current_write_reg = regaddr;
-					goto handle_type1_payload;
-				}
-
-				if (0) {
-			handle_type1_payload:
-					start_write(regaddr, false);
-					cursor++;
-
-					uint32_t last_word = wcount ? ~configdata.at(cursor) : 0;
-					bool in_continue = false;
-
-					while (wcount--) {
-						if (FLAGS_m) {
-							uint32_t this_word = configdata.at(cursor);
-							if (FLAGS_c && last_word == this_word) {
-								if (!in_continue)
-									printf("*\n");
-								in_continue = true;
-							} else {
-								if (current_write_reg == REG_FAR) {
-									frameid fid(this_word);
-									printf("%8d: 0x%08x FAR: Type=%d, Top=%d, Row=%d, Col=%d, Minor=%d\n",
-											cursor, fid.get_value(), fid.get_type(), fid.get_topflag(),
-											fid.get_rowaddr(), fid.get_coladdr(), fid.get_minor());
-								} else
-									printf("%8d: 0x%08x\n", cursor, this_word);
-								in_continue = false;
-							}
-							last_word = this_word;
-						}
-						handle_write(regaddr, configdata.at(cursor), false);
-						cursor++;
-					}
-					continue;
-				}
-			}
-
-			// Type 2 Packet
-			if (cmd_header == 2)
-			{
-				if (FLAGS_m)
-					printf("%8d: 0x%08x Type 2 write\n", cursor, configdata.at(cursor));
-
-#if 1
-				printf("%8d: Type 2 write is not supported at the moment. Set BITSTREAM.GENERAL.PERFRAMECRC on your design.\n", cursor);
-				return 1;
-#else
-				int opcode = selbits(cmd, 28, 27);
-				int wcount = selbits(cmd, 26, 0);
-
-				if (opcode != 2)
-					goto cmderror;
-
-				uint32_t last_word = configdata.at(cursor);
-				bool in_continue = false;
-
-				start_write(regaddr, true);
-
-				cursor++;
-				while (wcount--)
-				{
-					uint32_t this_word = configdata.at(cursor);
-					handle_write(current_write_reg, this_word, true);
-
-					if (FLAGS_m) {
-						if (FLAGS_c && last_word == this_word) {
-							if (!in_continue)
-								printf("*\n");
-							in_continue = true;
-						} else {
-							in_continue = false;
-							printf("%8d: Payload: 0x%08x\n", cursor, this_word);
-						}
-					}
-
-					last_word = this_word;
-					cursor++;
-				}
-				continue;
-#endif
-			}
-
-		cmderror:
-			printf("%8d: Unknown config command: 0x%08x\n", cursor, cmd);
+		if (f == nullptr) {
+			printf("Can't open output file '%s' for writing!\n", FLAGS_o.c_str());
 			return 1;
 		}
+	} else {
+		fprintf(f, "\n");
+	}
 
-		printf("Number of configuration frames: %d\n", int(configframes.size()));
+	std::vector<std::vector<bool>> pgmdata;
+	std::vector<int> pgmsep;
 
-		FILE *f = stdout;
+	for (auto &it : config->frames())
+	{
+		if (FLAGS_z && it.second == zero_frame)
+			continue;
 
-		if (!FLAGS_o.empty())
-		{
-			f = fopen(FLAGS_o.c_str(), "w");
+		if (!frames.empty() && !frames.count(it.first))
+			continue;
 
-			if (f == nullptr) {
-				printf("Can't open output file '%s' for writing!\n", FLAGS_o.c_str());
-				return 1;
-			}
-		}
+		if (frame_range_begin != frame_range_end &&
+		    (it.first < frame_range_begin || frame_range_end <= it.first))
+			continue;
 
 		if (FLAGS_o.empty())
-			fprintf(f, "\n");
-
-		std::vector<std::vector<bool>> pgmdata;
-		std::vector<int> pgmsep;
-
-		for (auto &it : configframes)
-		{
-			if (FLAGS_z && it.second == zero_frame)
-				continue;
-
-			frameid fid(it.first);
-
-			if (!frames.empty() && !frames.count(fid.get_value()))
-				continue;
-
-			if (frame_range_begin != frame_range_end && (fid.get_value() < frame_range_begin || frame_range_end <= fid.get_value()))
-				continue;
-
-			if (FLAGS_o.empty())
-				printf("Frame 0x%08x (Type=%d Top=%d Row=%d Column=%d Minor=%d%s):\n", fid.get_value(), fid.get_type(), fid.get_topflag(),
-						fid.get_rowaddr(), fid.get_coladdr(), fid.get_minor(), configframes_autoincr.count(fid.get_value()) ? " AUTO_INCREMENT" : "");
-
-			if (it.second.size() != 101) {
-				printf(" unusual frame size: %d\n", int(it.second.size()));
-				return 1;
-			}
-
-			if (FLAGS_p)
-			{
-				if (fid.get_minor() == 0 && !pgmdata.empty())
-					pgmsep.push_back(pgmdata.size());
-
-				pgmdata.push_back(std::vector<bool>());
-
-				for (int i = 0; i < 101; i++)
-				for (int k = 0; k < 32; k++)
-					pgmdata.back().push_back((it.second.at(i) & (1 << k)) != 0);
-			}
-			else
-			if (FLAGS_x || FLAGS_y)
-			{
-				for (int i = 0; i < 101; i++)
-				for (int k = 0; k < 32; k++)
-					if ((i != 50 || k > 12 || FLAGS_C) && ((it.second.at(i) & (1 << k)) != 0)) {
-						if (FLAGS_x)
-							fprintf(f, "bit_%08x_%03d_%02d_t%d_h%d_r%d_c%d_m%d\n",
-									fid.get_value(), i, k, fid.get_type(), fid.get_topflag(), fid.get_rowaddr(),
-									fid.get_coladdr(), fid.get_minor());
-						else
-							fprintf(f, "bit_%08x_%03d_%02d\n", fid.get_value(), i, k);
-					}
-				if (FLAGS_o.empty())
-					fprintf(f, "\n");
-			}
-			else
-			{
-				if (!FLAGS_o.empty())
-					fprintf(f, ".frame 0x%08x%s\n", fid.get_value(), configframes_autoincr.count(fid.get_value()) ? " AI" : "");
-
-				for (int i = 0; i < 101; i++)
-					fprintf(f, "%08x%s", it.second.at(i) & ((i != 50 || FLAGS_C) ? 0xffffffff : 0xffffe000), (i % 6) == 5 ? "\n" : " ");
-				fprintf(f, "\n\n");
-			}
-		}
+			printf("Frame 0x%08x (Type=%d Top=%d Row=%d Column=%d Minor=%d):\n",
+			       static_cast<uint32_t>(it.first), static_cast<unsigned int>(it.first.block_type()),
+			       it.first.is_bottom_half_rows() ? 1 : 0,
+			       it.first.row_address(), it.first.column_address(), it.first.minor_address());
 
 		if (FLAGS_p)
 		{
-			int width = pgmdata.size() + pgmsep.size();
-			int height = 101*32+100;
-			fprintf(f, "P5 %d %d 15\n", width, height);
+			if (it.first.minor_address() == 0 && !pgmdata.empty())
+				pgmsep.push_back(pgmdata.size());
 
-			for (int y = 0, bit = 101*32-1; y < height; y++, bit--)
+			pgmdata.push_back(std::vector<bool>());
+
+			for (int i = 0; i < 101; i++)
+			for (int k = 0; k < 32; k++)
+				pgmdata.back().push_back((it.second.at(i) & (1 << k)) != 0);
+		}
+		else
+		if (FLAGS_x || FLAGS_y)
+		{
+			for (int i = 0; i < 101; i++)
+			for (int k = 0; k < 32; k++)
+				if ((i != 50 || k > 12 || FLAGS_C) && ((it.second.at(i) & (1 << k)) != 0)) {
+					if (FLAGS_x)
+						fprintf(f, "bit_%08x_%03d_%02d_t%d_h%d_r%d_c%d_m%d\n",
+							static_cast<uint32_t>(it.first),
+							i, k,
+							static_cast<unsigned int>(it.first.block_type()),
+							it.first.is_bottom_half_rows() ? 1 : 0,
+							it.first.row_address(), it.first.column_address(), it.first.minor_address());
+					else
+						fprintf(f, "bit_%08x_%03d_%02d\n", static_cast<uint32_t>(it.first), i, k);
+				}
+			if (FLAGS_o.empty())
+				fprintf(f, "\n");
+		}
+		else
+		{
+			if (!FLAGS_o.empty())
+				fprintf(f, ".frame 0x%08x\n", static_cast<uint32_t>(it.first));
+
+			for (int i = 0; i < 101; i++)
+				fprintf(f, "%08x%s", it.second.at(i) & ((i != 50 || FLAGS_C) ? 0xffffffff : 0xffffe000), (i % 6) == 5 ? "\n" : " ");
+			fprintf(f, "\n\n");
+		}
+	}
+
+	if (FLAGS_p)
+	{
+		int width = pgmdata.size() + pgmsep.size();
+		int height = 101*32+100;
+		fprintf(f, "P5 %d %d 15\n", width, height);
+
+		for (int y = 0, bit = 101*32-1; y < height; y++, bit--)
+		{
+			for (int x = 0, frame = 0, sep = 0; x < width; x++, frame++)
 			{
-				for (int x = 0, frame = 0, sep = 0; x < width; x++, frame++)
-				{
-					if (sep < int(pgmsep.size()) && frame == pgmsep.at(sep)) {
-						fputc(8, f);
-						x++, sep++;
-					}
-
-					fputc(pgmdata.at(frame).at(bit) ? 15 : 0, f);
+				if (sep < int(pgmsep.size()) && frame == pgmsep.at(sep)) {
+					fputc(8, f);
+					x++, sep++;
 				}
 
-				if (bit % 32 == 0 && y) {
-					for (int x = 0; x < width; x++)
-						fputc(8, f);
-					y++;
-				}
+				fputc(pgmdata.at(frame).at(bit) ? 15 : 0, f);
+			}
+
+			if (bit % 32 == 0 && y) {
+				for (int x = 0; x < width; x++)
+					fputc(8, f);
+				y++;
 			}
 		}
-
-		if (!FLAGS_o.empty())
-			fclose(f);
 	}
 
+	if (!FLAGS_o.empty())
+		fclose(f);
+
 	printf("DONE\n");
 	return 0;
 }