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Have circle buffer work when memory is misaligned

This commit is contained in:
Jeffrey Pfau 2014-01-16 01:56:17 -08:00
parent 39025dedff
commit 4e88cc86d9
1 changed files with 58 additions and 2 deletions
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60
src/util/circle-buffer.c
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@ -3,6 +3,21 @@
#include <stddef.h>
#include <stdlib.h>
#ifndef NDEBUG
static int _checkIntegrity(struct CircleBuffer* buffer) {
if ((int8_t*) buffer->writePtr - (int8_t*) buffer->readPtr == buffer->size) {
return 1;
}
if (buffer->capacity - buffer->size == ((int8_t*) buffer->writePtr - (int8_t*) buffer->readPtr)) {
return 1;
}
if (buffer->capacity - buffer->size == ((int8_t*) buffer->readPtr - (int8_t*) buffer->writePtr)) {
return 1;
}
return 0;
}
#endif
void CircleBufferInit(struct CircleBuffer* buffer, unsigned capacity) {
buffer->data = malloc(capacity);
buffer->capacity = capacity;
@ -34,6 +49,11 @@ int CircleBufferWrite8(struct CircleBuffer* buffer, int8_t value) {
buffer->writePtr = buffer->data;
}
buffer->size += sizeof(int8_t);
#ifndef NDEBUG
if (!_checkIntegrity(buffer)) {
abort();
}
#endif
return 1;
}
@ -42,6 +62,14 @@ int CircleBufferWrite32(struct CircleBuffer* buffer, int32_t value) {
if (buffer->size + sizeof(int32_t) > buffer->capacity) {
return 0;
}
if ((intptr_t) data & 0x3) {
int written = 0;
written += CircleBufferWrite8(buffer, ((int8_t*) &value)[0]);
written += CircleBufferWrite8(buffer, ((int8_t*) &value)[1]);
written += CircleBufferWrite8(buffer, ((int8_t*) &value)[2]);
written += CircleBufferWrite8(buffer, ((int8_t*) &value)[3]);
return written;
}
*data = value;
++data;
size_t size = (int8_t*) data - (int8_t*) buffer->data;
@ -51,7 +79,12 @@ int CircleBufferWrite32(struct CircleBuffer* buffer, int32_t value) {
buffer->writePtr = buffer->data;
}
buffer->size += sizeof(int32_t);
return 1;
#ifndef NDEBUG
if (!_checkIntegrity(buffer)) {
abort();
}
#endif
return 4;
}
int CircleBufferRead8(struct CircleBuffer* buffer, int8_t* value) {
@ -68,6 +101,11 @@ int CircleBufferRead8(struct CircleBuffer* buffer, int8_t* value) {
buffer->readPtr = buffer->data;
}
buffer->size -= sizeof(int8_t);
#ifndef NDEBUG
if (!_checkIntegrity(buffer)) {
abort();
}
#endif
return 1;
}
@ -76,6 +114,14 @@ int CircleBufferRead32(struct CircleBuffer* buffer, int32_t* value) {
if (buffer->size < sizeof(int32_t)) {
return 0;
}
if ((intptr_t) data & 0x3) {
int read = 0;
read += CircleBufferRead8(buffer, &((int8_t*) value)[0]);
read += CircleBufferRead8(buffer, &((int8_t*) value)[1]);
read += CircleBufferRead8(buffer, &((int8_t*) value)[2]);
read += CircleBufferRead8(buffer, &((int8_t*) value)[3]);
return read;
}
*value = *data;
++data;
size_t size = (int8_t*) data - (int8_t*) buffer->data;
@ -85,7 +131,12 @@ int CircleBufferRead32(struct CircleBuffer* buffer, int32_t* value) {
buffer->readPtr = buffer->data;
}
buffer->size -= sizeof(int32_t);
return 1;
#ifndef NDEBUG
if (!_checkIntegrity(buffer)) {
abort();
}
#endif
return 4;
}
int CircleBufferRead(struct CircleBuffer* buffer, void* output, size_t length) {
@ -111,5 +162,10 @@ int CircleBufferRead(struct CircleBuffer* buffer, void* output, size_t length) {
}
buffer->size -= length;
#ifndef NDEBUG
if (!_checkIntegrity(buffer)) {
abort();
}
#endif
return length;
}