diff options
author | Marc Schink <jaylink-dev@marcschink.de> | 2014-08-28 12:06:21 +0200 |
---|---|---|
committer | Marc Schink <jaylink-dev@marcschink.de> | 2015-03-02 03:20:27 -0500 |
commit | 497a76045f677ee04dc3ef3e58c8fce5320e040a (patch) | |
tree | b67477ff7023b7932df0164a7dc5094ccf96739d /libjaylink/buffer.c | |
parent | 2fbc71dd90f48c17cf5776476752a94d268d56f3 (diff) | |
download | libjaylink-497a76045f677ee04dc3ef3e58c8fce5320e040a.zip libjaylink-497a76045f677ee04dc3ef3e58c8fce5320e040a.tar.gz libjaylink-497a76045f677ee04dc3ef3e58c8fce5320e040a.tar.bz2 |
Add helper functions to deal with data of a device.
Diffstat (limited to 'libjaylink/buffer.c')
-rw-r--r-- | libjaylink/buffer.c | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/libjaylink/buffer.c b/libjaylink/buffer.c new file mode 100644 index 0000000..49103ca --- /dev/null +++ b/libjaylink/buffer.c @@ -0,0 +1,130 @@ +/* + * This file is part of the libjaylink project. + * + * Copyright (C) 2014 Marc Schink <jaylink-dev@marcschink.de> + * + * 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, either version 3 of the License, or + * (at your option) any later version. + * + * 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, see <http://www.gnu.org/licenses/>. + */ + +#include <stdlib.h> +#include <stdint.h> +#include <string.h> + +#include "config.h" + +/** + * Write a 16-bit unsigned integer value to a buffer. + * + * The value is stored in the buffer in device byte order. + * + * @param buffer Buffer to write the value into. + * @param value Value to write into the buffer in host byte order. + * @param offset Offset of the value within the buffer in bytes. + */ +void buffer_set_u16(uint8_t *buffer, uint16_t value, size_t offset) +{ + /* + * Store the value in the buffer and swap byte order depending on the + * host byte order. + */ +#ifdef WORDS_BIGENDIAN + buffer[offset + 0] = value; + buffer[offset + 1] = value >> 8; +#else + memcpy(buffer + offset, &value, sizeof(value)); +#endif +} + +/** + * Read a 16-bit unsigned integer value from a buffer. + * + * The value in the buffer is expected to be stored in device byte order. + * + * @param buffer Buffer to read the value from. + * @param offset Offset of the value within the buffer in bytes. + * + * @return The value read from the buffer in host byte order. + */ +uint16_t buffer_get_u16(const uint8_t *buffer, size_t offset) +{ + uint16_t value; + + /* + * Read the value from the buffer and swap byte order depending on the + * host byte order. + */ +#ifdef WORDS_BIGENDIAN + value = (((uint16_t)buffer[offset + 1])) | \ + (((uint16_t)buffer[offset + 0]) << 8); +#else + memcpy(&value, buffer + offset, sizeof(value)); +#endif + + return value; +} + +/** + * Write a 32-bit unsigned integer value to a buffer. + * + * The value is stored in the buffer in device byte order. + * + * @param buffer Buffer to write the value into. + * @param value Value to write into the buffer in host byte order. + * @param offset Offset of the value within the buffer in bytes. + */ +void buffer_set_u32(uint8_t *buffer, uint32_t value, size_t offset) +{ + /* + * Store the value in the buffer and swap byte order depending on the + * host byte order. + */ +#ifdef WORDS_BIGENDIAN + buffer[offset + 0] = value; + buffer[offset + 1] = value >> 8; + buffer[offset + 2] = value >> 16; + buffer[offset + 3] = value >> 24; +#else + memcpy(buffer + offset, &value, sizeof(value)); +#endif +} + +/** + * Read a 32-bit unsigned integer value from a buffer. + * + * The value in the buffer is expected to be stored in device byte order. + * + * @param buffer Buffer to read the value from. + * @param offset Offset of the value within the buffer in bytes. + * + * @return The value read from the buffer in host byte order. + */ +uint32_t buffer_get_u32(const uint8_t *buffer, size_t offset) +{ + uint32_t value; + + /* + * Read the value from the buffer and swap byte order depending on the + * host byte order. + */ +#ifdef WORDS_BIGENDIAN + value = (((uint32_t)buffer[offset + 3])) | \ + (((uint32_t)buffer[offset + 2]) << 8) | \ + (((uint32_t)buffer[offset + 1]) << 16) | \ + (((uint32_t)buffer[offset + 0]) << 24); +#else + memcpy(&value, buffer + offset, sizeof(value)); +#endif + + return value; +} |