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diff --git a/src/stmf0/ao_crc_stm.c b/src/stmf0/ao_crc_stm.c
new file mode 100644
index 00000000..78efa93a
--- /dev/null
+++ b/src/stmf0/ao_crc_stm.c
@@ -0,0 +1,90 @@
+/*
+ * Copyright © 2015 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include <ao.h>
+#include <ao_crc.h>
+
+#ifndef AO_CRC_WIDTH
+#error "Must define AO_CRC_WIDTH"
+#endif
+
+/* Only the STM32F07x and ST32F09x series have
+ * programmable CRC units. Others can only do the ANSI CRC-32 computation
+ */
+
+#if !AO_HAVE_PROGRAMMABLE_CRC_UNIT && AO_CRC_WIDTH != 32
+#error "Target hardware does not have programmable CRC unit"
+#endif
+
+#ifndef AO_CRC_POLY
+#if AO_CRC_WIDTH == 16
+#define AO_CRC_POLY	AO_CRC_16_DEFAULT
+#endif
+#if AO_CRC_WIDTH == 32
+#define AO_CRC_POLY	AO_CRC_32_DEFAULT
+#endif
+#endif
+
+#if !AO_HAVE_PROGRAMMABLE_CRC_UNIT && (AO_CRC_WIDTH != 32 || AO_CRC_POLY != AO_CRC_32_ANSI)
+#error "Target hardware does not have programmable CRC unit"
+#endif
+
+#if AO_CRC_WIDTH == 32
+#define AO_CRC_CR_POLYSIZE	STM_CRC_CR_POLYSIZE_32
+#endif
+
+#if AO_CRC_WIDTH == 16
+#define AO_CRC_CR_POLYSIZE	STM_CRC_CR_POLYSIZE_16
+#endif
+
+#if AO_CRC_WIDTH == 8
+#define AO_CRC_CR_POLYSIZE	STM_CRC_CR_POLYSIZE_8
+#endif
+
+#if AO_CRC_WIDTH == 7
+#define AO_CRC_CR_POLYSIZE	STM_CRC_CR_POLYSIZE_7
+#endif
+
+#ifndef AO_CRC_INIT
+#define AO_CRC_INIT	0xffffffff;
+#endif
+
+void
+ao_crc_reset(void)
+{
+	stm_crc.cr |= (1 << STM_CRC_CR_RESET);
+	while ((stm_crc.cr & (1 << STM_CRC_CR_RESET)) != 0)
+		;
+}
+
+void
+ao_crc_init(void)
+{
+	/* Turn on the CRC clock */
+	stm_rcc.ahbenr |= (1 << STM_RCC_AHBENR_CRCEN);
+
+	/* Need to initialize CR even on non-programmable hardware,
+	 * the write to the POLYSIZE bits will be ignored in that
+	 * case
+	 */
+	stm_crc.cr = (AO_CRC_CR_POLYSIZE << STM_CRC_CR_POLYSIZE);
+	stm_crc.init = AO_CRC_INIT;
+#if AO_HAVE_PROGRAMMABLE_CRC_UNIT
+	stm_crc.pol = AO_CRC_POLY;
+#endif
+	ao_crc_reset();
+}