--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cp2102/intel_hex_in.c	Mon Sep 11 19:45:56 2023 +0000
@@ -0,0 +1,148 @@
+/*
+ * This module implements a function for reading CP2102 EEPROM images
+ * in the Intel HEX format which we've copied from cp210x-program-1.0,
+ * the Python-language tool from 2014.
+ */
+
+#include <sys/types.h>
+#include <ctype.h>
+#include <string.h>
+#include <strings.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include "cp210x_defs.h"
+
+extern u_char eeprom[SIZE_EEPROM];
+
+static int
+decode_hex_digit(c)
+{
+	if (c >= '0' && c <= '9')
+		return(c - '0');
+	if (c >= 'A' && c <= 'F')
+		return(c - 'A' + 10);
+	if (c >= 'a' && c <= 'f')
+		return(c - 'a' + 10);
+	return(-1);
+}
+
+static int
+decode_hex_byte(str)
+	char *str;
+{
+	int u, l;
+
+	u = decode_hex_digit(str[0]);
+	l = decode_hex_digit(str[1]);
+	return (u << 4) | l;
+}
+
+void
+read_intel_hex(filename)
+	char *filename;
+{
+	FILE *inf;
+	char linebuf[1024], *cp;
+	int lineno;
+	unsigned eeprom_offset;
+	unsigned payload_len, record_len, n;
+	u_char record[21], csum;
+	unsigned record_addr, expect_addr;
+
+	inf = fopen(filename, "r");
+	if (!inf) {
+		perror(filename);
+		exit(1);
+	}
+	eeprom_offset = 0;
+	for (lineno = 1; fgets(linebuf, sizeof linebuf, inf); lineno++) {
+		if (!index(linebuf, '\n')) {
+			fprintf(stderr,
+				"%s line %d: too long or missing newline\n",
+				filename, lineno);
+			exit(1);
+		}
+		if (linebuf[0] != ':')
+			continue;
+		if (!isxdigit(linebuf[1]) || !isxdigit(linebuf[2])) {
+inv_record:		fprintf(stderr,
+				"%s line %d: invalid Intex HEX record\n",
+				filename, lineno);
+			exit(1);
+		}
+		payload_len = decode_hex_byte(linebuf + 1);
+		if (payload_len > 16) {
+bad_payload_len:	fprintf(stderr,
+				"%s line %d: unsupported payload length\n",
+				filename, lineno);
+			exit(1);
+		}
+		record_len = payload_len + 5;
+		cp = linebuf + 1;
+		csum = 0;
+		for (n = 0; n < payload_len; n++) {
+			if (!isxdigit(cp[0]) || !isxdigit(cp[1]))
+				goto inv_record;
+			record[n] = decode_hex_byte(cp);
+			cp += 2;
+			csum += record[n];
+		}
+		if (csum) {
+			fprintf(stderr,
+				"%s line %d: bad Intel HEX record checksum\n",
+				filename, lineno);
+			exit(1);
+		}
+		if (record[3] == 0x00) {
+			if (payload_len != 16)
+				goto bad_payload_len;
+			if (eeprom_offset >= SIZE_EEPROM) {
+				fprintf(stderr,
+			"%s line %d: data continues past valid EEPROM size\n",
+					filename, lineno);
+				exit(1);
+			}
+			record_addr = (record[1] << 8) | record[2];
+			expect_addr = EEPROM_START_ADDR + eeprom_offset;
+			if (record_addr != expect_addr) {
+				fprintf(stderr,
+			"%s line %d: record addr is %04X, but we expect %04X\n",
+					filename, lineno, record_addr,
+					expect_addr);
+				exit(1);
+			}
+			bcopy(record + 4, eeprom + eeprom_offset, 16);
+			eeprom_offset += 16;
+		} else if (record[3] == 0x01) {
+			if (payload_len) {
+				fprintf(stderr,
+		"%s line %d: nonzero payload length in end-marker record\n",
+					filename, lineno);
+				exit(1);
+			}
+			if (eeprom_offset < SIZE_EEPROM) {
+				fprintf(stderr,
+				"%s line %d: end-marker without full data\n",
+					filename, lineno);
+				exit(1);
+			}
+			break;
+		} else {
+			fprintf(stderr,
+			"%s line %d: unsupported Intel HEX record type\n",
+				filename, lineno);
+			exit(1);
+		}
+	}
+	fclose(inf);
+	if (!eeprom_offset) {
+		fprintf(stderr, "error: no Intel HEX EEPROM data found in %s\n",
+			filename);
+		exit(1);
+	}
+	if (eeprom_offset < SIZE_EEPROM) {
+		fprintf(stderr, "error: %s contains truncated data\n",
+			filename);
+		exit(1);
+	}
+}