Add cs_hex_decode()

CL: Add cs_hex_decode()

include/common/cs_hex.h

@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2014-2018 Cesanta Software Limited
+ * All rights reserved
+ *
+ * Licensed under the Apache License, Version 2.0 (the ""License"");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an ""AS IS"" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * Decodes a hex-encoded string `s` length `len` into `dst`.
+ * `dst` must have enough space to hold the result.
+ * `*dec_len` will contain the resulting length of the string in `dst`
+ * while return value will return number of processed bytes in `src`.
+ * Return value == len indicates successful processing of all the data.
+ */
+int cs_hex_decode(const char *s, int len, unsigned char *dst, int *dst_len);
+
+#ifdef __cplusplus
+}
+#endif

include/mgos.h

@@ -24,6 +24,7 @@
 
 #include "common/cs_dbg.h"
 #include "common/cs_file.h"
+#include "common/cs_hex.h"
 #include "common/json_utils.h"
 #include "common/mbuf.h"
 #include "common/str_util.h"

platforms/cc3200/Makefile.build

@@ -141,7 +141,7 @@ MGOS_SRCS += mgos_event.c \
              mgos_config_util.c mgos_sys_config.c \
              mgos_dlsym.c mgos_system.c \
              $(notdir $(MGOS_CONFIG_C)) $(notdir $(MGOS_RO_VARS_C)) \
-             cs_crc32.c cs_file.c \
+             cs_crc32.c cs_file.c cs_hex.c \
              cs_frbuf.c mgos_file_utils.c mgos_utils.c \
              cs_rbuf.c mgos_core_dump.c mgos_uart.c \
              boot.c frozen.c json_utils.c

platforms/cc3220/Makefile.build

@@ -174,7 +174,7 @@ VPATH += $(SDK_PATH)/source/ti/devices/cc32xx/driverlib \
 SDK_CFLAGS = -DTARGET_IS_CC3220 -DUSE_CC3220_ROM_DRV_API -DUSE_FREERTOS
 
 MGOS_SRCS += $(notdir $(wildcard $(MGOS_CC3220_PATH)/src/*.c)) \
-             cs_crc32.c cs_file.c cs_rbuf.c \
+             cs_crc32.c cs_file.c cs_hex.c cs_rbuf.c \
              frozen.c json_utils.c \
              mgos_config_util.c mgos_core_dump.c mgos_debug.c mgos_dlsym.c mgos_event.c mgos_gpio.c \
              mgos_file_utils.c mgos_init.c \

platforms/esp32/src/esp32_src.mk

@@ -45,7 +45,7 @@ MGOS_SRCS += mgos_config_util.c mgos_core_dump.c mgos_dlsym.c mgos_event.c \
 VPATH += $(MGOS_ESP_SRC_PATH) $(MGOS_PATH)/common \
          $(MGOS_PATH)/common/platforms/esp/src
 
-MGOS_SRCS += cs_crc32.c cs_file.c cs_rbuf.c json_utils.c
+MGOS_SRCS += cs_crc32.c cs_file.c cs_hex.c cs_rbuf.c json_utils.c
 
 VPATH += $(MGOS_VPATH)
 

platforms/esp8266/Makefile.build

@@ -77,7 +77,7 @@ include $(MGOS_ESP8266_PATH)/common.mk
 
 MGOS_ESP_SRC_PATH = $(MGOS_ESP8266_PATH)/src
 
-MGOS_SRCS += cs_file.c cs_rbuf.c \
+MGOS_SRCS += cs_file.c cs_hex.c cs_rbuf.c \
              mgos_config_util.c \
              mgos_core_dump.c \
              mgos_dlsym.c \

platforms/rs14100/Makefile.build

@@ -136,7 +136,7 @@ FFI_EXPORTS_C = $(GEN_DIR)/ffi_exports.c
 MGOS_SRCS += $(notdir $(MGOS_CONFIG_C)) $(notdir $(MGOS_RO_VARS_C)) \
              mgos_config_util.c mgos_core_dump.c mgos_event.c mgos_gpio.c \
              mgos_hw_timers.c mgos_sys_config.c \
-             mgos_time.c mgos_timers.c cs_crc32.c cs_file.c \
+             mgos_time.c mgos_timers.c cs_crc32.c cs_file.c cs_hex.c \
              json_utils.c frozen.c mgos_uart.c cs_rbuf.c mgos_init.c \
              mgos_dlsym.c mgos_file_utils.c mgos_system.c mgos_utils.c \
              arm_exc_top.S arm_exc.c arm_nsleep100.c arm_nsleep100_m4.S \

platforms/stm32/Makefile.build

@@ -153,7 +153,7 @@ FFI_EXPORTS_C = $(GEN_DIR)/ffi_exports.c
 MGOS_SRCS += $(notdir $(MGOS_CONFIG_C)) $(notdir $(MGOS_RO_VARS_C)) \
              mgos_config_util.c mgos_core_dump.c mgos_event.c mgos_gpio.c \
              mgos_hw_timers.c mgos_sys_config.c \
-             mgos_time.c mgos_timers.c cs_crc32.c cs_file.c \
+             mgos_time.c mgos_timers.c cs_crc32.c cs_file.c cs_hex.c \
              json_utils.c frozen.c mgos_uart.c cs_rbuf.c mgos_init.c \
              mgos_dlsym.c mgos_file_utils.c mgos_system.c mgos_utils.c \
              arm_exc_top.S arm_exc.c arm_nsleep100.c \

platforms/ubuntu/Makefile.build

@@ -48,7 +48,7 @@ MGOS_SRCS = $(notdir $(wildcard *.c)) mgos_init.c  \
             mgos_system.c mgos_time.c mgos_timers.c \
             mgos_config_util.c mgos_sys_config.c \
             json_utils.c cs_rbuf.c mgos_uart.c \
-            mgos_utils.c cs_file.c cs_crc32.c
+            mgos_utils.c cs_file.c cs_hex.c cs_crc32.c
 
 PLATFORM_SRCS = $(wildcard $(PLATFORM_VPATH)/*.c)
 

src/common/cs_hex.c

@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2014-2018 Cesanta Software Limited
+ * All rights reserved
+ *
+ * Licensed under the Apache License, Version 2.0 (the ""License"");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an ""AS IS"" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "common/cs_hex.h"
+
+#include <ctype.h>
+
+static int hextoi(int x) {
+  return (x >= '0' && x <= '9' ? x - '0' : x - 'W');
+}
+
+int cs_hex_decode(const char *s, int len, unsigned char *dst, int *dst_len) {
+  int i = 0;
+  unsigned char *p = dst;
+  while (i < len) {
+    int c1, c2;
+    c1 = hextoi(tolower((int) s[i++]));
+    if (c1 < 0 || c1 > 15 || i == len) {
+      i--;
+      break;
+    }
+    c2 = hextoi(tolower((int) s[i++]));
+    if (c2 < 0 || c2 > 15) {
+      i -= 2;
+      break;
+    }
+    *p++ = (unsigned char) ((c1 << 4) | c2);
+  }
+  *dst_len = (int) (p - dst);
+  return i;
+}

src/test/Makefile

@@ -17,6 +17,7 @@ SOURCES = unit_test.c \
           $(REPO_ROOT)/src/mgos_event.c \
           $(REPO_ROOT)/src/common/json_utils.c \
           $(REPO_ROOT)/src/common/cs_file.c \
+          $(REPO_ROOT)/src/common/cs_hex.c \
           $(MONGOOSE_PATH)/mongoose.c \
           test_main.c \
           test_util.c

src/test/unit_test.c

@@ -5,6 +5,7 @@
 
 #include "common/cs_dbg.h"
 #include "common/cs_file.h"
+#include "common/cs_hex.h"
 
 #include "frozen.h"
 
@@ -202,13 +203,47 @@ static const char *test_events(void) {
   return NULL;
 }
 
+static const char *test_cs_hex(void) {
+  unsigned char dst[32];
+  int dst_len = 0;
+  ASSERT_EQ(cs_hex_decode(NULL, 0, NULL, &dst_len), 0);
+  {
+    const char *s = "11";
+    ASSERT_EQ(cs_hex_decode(s, strlen(s), dst, &dst_len), strlen(s));
+    ASSERT_EQ(dst_len, 1);
+    ASSERT_EQ(dst[0], 0x11);
+  }
+  {
+    const char *s = "A1b200";
+    ASSERT_EQ(cs_hex_decode(s, strlen(s), dst, &dst_len), strlen(s));
+    ASSERT_EQ(dst_len, 3);
+    ASSERT_EQ(dst[0], 0xa1);
+    ASSERT_EQ(dst[1], 0xb2);
+    ASSERT_EQ(dst[2], 0x00);
+  }
+  {
+    const char *s = "A1b";
+    ASSERT_EQ(cs_hex_decode(s, strlen(s), dst, &dst_len), 2);
+    ASSERT_EQ(dst_len, 1);
+    ASSERT_EQ(dst[0], 0xa1);
+  }
+  {
+    const char *s = "A1x200";
+    ASSERT_EQ(cs_hex_decode(s, strlen(s), dst, &dst_len), 2);
+    ASSERT_EQ(dst_len, 1);
+    ASSERT_EQ(dst[0], 0xa1);
+  }
+  return NULL;
+}
+
 void tests_setup(void) {
 }
 
 const char *tests_run(const char *filter) {
   RUN_TEST(test_config);
   RUN_TEST(test_json_scanf);
   RUN_TEST(test_events);
+  RUN_TEST(test_cs_hex);
   return NULL;
 }