ref: f700744969ac867649aa581ae19447a4c172179e
dir: /midiproc/buffer.c/
// // Copyright(C) 2017 Alex Mayfield // // 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 2 // 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. // // DESCRIPTION: // A simple buffer and reader implementation. // #ifdef _WIN32 #include "buffer.h" #include <stdlib.h> #include <stddef.h> // // Create a new buffer. // buffer_t *NewBuffer() { buffer_t *buf = malloc(sizeof(buffer_t)); buf->buffer_end = buf->buffer + BUFFER_SIZE; Buffer_Clear(buf); return buf; } // // Free a buffer. // void DeleteBuffer(buffer_t *buf) { free(buf); } // // Return the data in the buffer. // int Buffer_Data(buffer_t *buf, byte **data) { *data = buf->data; return buf->data_len; } // // Push data onto the end of the buffer. // boolean Buffer_Push(buffer_t *buf, const void *data, int len) { ptrdiff_t space_begin, space_end; if (len <= 0) { // Do nothing, successfully. return true; } space_begin = buf->data - buf->buffer; space_end = buf->buffer_end - buf->data_end; if (len > space_end) { if (len > space_begin + space_end) { // Don't overflow the buffer. return false; } // Move our data to the front of the buffer. memmove(buf->buffer, buf->data, buf->data_len); buf->data = buf->buffer; buf->data_end = buf->buffer + buf->data_len; } // Append to the buffer. memcpy(buf->data_end, data, len); buf->data_len += len; buf->data_end = buf->data + buf->data_len; return true; } // // Shift len bytes off of the front of the buffer. // void Buffer_Shift(buffer_t *buf, int len) { ptrdiff_t max_shift; if (len <= 0) { // Do nothing. return; } max_shift = buf->data_end - buf->data; if (len >= max_shift) { // If the operation would clear the buffer, just zero everything. Buffer_Clear(buf); } else { buf->data += len; buf->data_len -= len; } } // // Clear the buffer. // void Buffer_Clear(buffer_t *buf) { buf->data = buf->buffer; buf->data_end = buf->buffer; buf->data_len = 0; } // // Create a new buffer reader. // // WARNING: This reader will invalidate if the underlying buffer changes. // Use it, then delete it before you touch the underlying buffer again. // buffer_reader_t *NewReader(buffer_t* buffer) { buffer_reader_t *reader = malloc(sizeof(buffer_reader_t)); reader->buffer = buffer; reader->pos = buffer->data; return reader; } // // Delete a buffer reader. // void DeleteReader(buffer_reader_t *reader) { free(reader); } // // Count the number of bytes read thus far. // int Reader_BytesRead(buffer_reader_t *reader) { return reader->pos - reader->buffer->data; } // // Read an unsigned byte from a buffer. // boolean Reader_ReadInt8(buffer_reader_t *reader, uint8_t *out) { byte *data, *data_end; int len = Buffer_Data(reader->buffer, &data); data_end = data + len; if (data_end - reader->pos < 1) { return false; } *out = (uint8_t)*reader->pos; reader->pos += 1; return true; } // // Read an unsigned short from a buffer. // boolean Reader_ReadInt16(buffer_reader_t *reader, uint16_t *out) { byte *data, *data_end, *dp; int len = Buffer_Data(reader->buffer, &data); data_end = data + len; dp = reader->pos; if (data_end - reader->pos < 2) { return false; } *out = (uint16_t)((dp[0] << 8) | dp[1]); reader->pos += 2; return true; } // // Read an unsigned int from a buffer. // boolean Reader_ReadInt32(buffer_reader_t *reader, uint32_t *out) { byte *data, *data_end, *dp; int len = Buffer_Data(reader->buffer, &data); data_end = data + len; dp = reader->pos; if (data_end - reader->pos < 4) { return false; } *out = (uint32_t)((dp[0] << 24) | (dp[1] << 16) | (dp[2] << 8) | dp[3]); reader->pos += 4; return true; } // // Read a string from a buffer. // char *Reader_ReadString(buffer_reader_t *reader) { byte *data, *data_start, *data_end, *dp; int len = Buffer_Data(reader->buffer, &data); data_start = reader->pos; data_end = data + len; dp = reader->pos; while (dp < data_end && *dp != '\0') { dp++; } if (dp >= data_end) { // Didn't see a null terminator, not a complete string. return NULL; } reader->pos = dp + 1; return (char*)data_start; } #endif // #ifdef _WIN32