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Viewing changes to io/ArrayWriter.c

  • Committer: cjdelisle
  • Date: 2011-02-16 23:03:00 UTC
  • Revision ID: git-v1:d475c9c10adc25590bea5e7dc5383b32f66d5eb8
First commit for cjdns.

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io/ArrayWriter.c
 
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#include "ArrayWriter.h"
 
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#include <string.h>
 
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struct ArrayWriter_context {
 
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    char* beginPointer;
 
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    char* pointer;
 
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    char* endPointer;
 
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    int returnCode;
 
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};
 
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static int write(void* toWrite, size_t length, struct Writer* writer);
 
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static uint64_t bytesWritten(struct Writer* writer);
 
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/** @see ArrayWriter.h */
 
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struct Writer* ArrayWriter_new(void* writeToBuffer,
 
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                               size_t length,
 
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                               struct MemAllocator* allocator)
 
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{
 
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    struct Writer* writer =
 
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        allocator->calloc(sizeof(struct Writer), 1, allocator);
 
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    struct ArrayWriter_context* context =
 
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        allocator->calloc(sizeof(struct ArrayWriter_context), 1, allocator);
 
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    if (context == NULL || writer == NULL) {
 
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        return NULL;
 
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    }
 
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    context->beginPointer = (char*) writeToBuffer;
 
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    context->pointer = (char*) writeToBuffer;
 
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    context->endPointer = (char*) writeToBuffer + length;
 
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    struct Writer localWriter = {
 
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        .context = context,
 
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        .write = write,
 
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        .bytesWritten = bytesWritten
 
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    };
 
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    memcpy(writer, &localWriter, sizeof(struct Writer));
 
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    return writer;
 
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}
 
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/** @see Writer->write() */
 
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static int write(void* toWrite, size_t length, struct Writer* writer)
 
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{
 
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    struct ArrayWriter_context* context =
 
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        (struct ArrayWriter_context*) writer->context;
 
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    /* If there was a previous failure then don't allow any more writing. */
 
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    if (context->returnCode != 0) {
 
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        return context->returnCode;
 
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    }
 
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    /* Prove that it doesn't run off the end of the buffer or roll over. */
 
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    if (context->pointer + length >= context->endPointer
 
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        || context->pointer + length < context->pointer)
 
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    {
 
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        context->returnCode = -1;
 
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        return -1;
 
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    }
 
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    memcpy(context->pointer, toWrite, length);
 
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    context->pointer += length;
 
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    return 0;
 
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}
 
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static uint64_t bytesWritten(struct Writer* writer)
 
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{
 
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    struct ArrayWriter_context* context =
 
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        (struct ArrayWriter_context*) writer->context;
 
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    return context->pointer - context->beginPointer;
 
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}