Diff: pb_encode.c

Revision:

0:c7beea49fc91

Child:

1:e08406101222

diff -r 000000000000 -r c7beea49fc91 pb_encode.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/pb_encode.c	Tue Feb 19 20:03:29 2013 +0000
@@ -0,0 +1,429 @@
+/* pb_encode.c -- encode a protobuf using minimal resources
+ *
+ * 2011 Petteri Aimonen <jpa@kapsi.fi>
+ */
+
+#define NANOPB_INTERNALS
+#include "pb.h"
+#include "pb_encode.h"
+#include <string.h>
+
+/* The warn_unused_result attribute appeared first in gcc-3.4.0 */
+#if !defined(__GNUC__) || ( __GNUC__ < 3) || (__GNUC__ == 3 && __GNUC_MINOR__ < 4)
+    #define checkreturn
+#else
+    /* Verify that we remember to check all return values for proper error propagation */
+    #define checkreturn __attribute__((warn_unused_result))
+#endif
+
+typedef bool (*pb_encoder_t)(pb_ostream_t *stream, const pb_field_t *field, const void *src) checkreturn;
+
+/* --- Function pointers to field encoders ---
+ * Order in the array must match pb_action_t LTYPE numbering.
+ */
+static const pb_encoder_t PB_ENCODERS[PB_LTYPES_COUNT] = {
+    &pb_enc_varint,
+    &pb_enc_svarint,
+    &pb_enc_fixed32,
+    &pb_enc_fixed64,
+    
+    &pb_enc_bytes,
+    &pb_enc_string,
+    &pb_enc_submessage
+};
+
+/* pb_ostream_t implementation */
+
+static bool checkreturn buf_write(pb_ostream_t *stream, const uint8_t *buf, size_t count)
+{
+    uint8_t *dest = (uint8_t*)stream->state;
+    stream->state = dest + count;
+    
+    while (count--)
+        *dest++ = *buf++;
+    
+    return true;
+}
+
+pb_ostream_t pb_ostream_from_buffer(uint8_t *buf, size_t bufsize)
+{
+    pb_ostream_t stream;
+#ifdef PB_BUFFER_ONLY
+    stream.callback = (void*)1; /* Just some marker value */
+#else
+    stream.callback = &buf_write;
+#endif
+    stream.state = buf;
+    stream.max_size = bufsize;
+    stream.bytes_written = 0;
+    return stream;
+}
+
+bool checkreturn pb_write(pb_ostream_t *stream, const uint8_t *buf, size_t count)
+{
+    if (stream->callback != NULL)
+    {
+        if (stream->bytes_written + count > stream->max_size)
+            return false;
+
+#ifdef PB_BUFFER_ONLY
+        if (!buf_write(stream, buf, count))
+            return false;
+#else        
+        if (!stream->callback(stream, buf, count))
+            return false;
+#endif
+    }
+    
+    stream->bytes_written += count;
+    return true;
+}
+
+/* Main encoding stuff */
+
+/* Callbacks don't need this function because they usually know the data type
+ * without examining the field structure.
+ * Therefore it is static for now.
+ */
+static bool checkreturn encode_array(pb_ostream_t *stream, const pb_field_t *field,
+                         const void *pData, size_t count, pb_encoder_t func)
+{
+    size_t i;
+    const void *p;
+    size_t size;
+    
+    if (count == 0)
+        return true;
+    
+    if (PB_LTYPE(field->type) <= PB_LTYPE_LAST_PACKABLE)
+    {
+        if (!pb_encode_tag(stream, PB_WT_STRING, field->tag))
+            return false;
+        
+        /* Determine the total size of packed array. */
+        if (PB_LTYPE(field->type) == PB_LTYPE_FIXED32)
+        {
+            size = 4 * count;
+        }
+        else if (PB_LTYPE(field->type) == PB_LTYPE_FIXED64)
+        {
+            size = 8 * count;
+        }
+        else
+        {
+            pb_ostream_t sizestream = {0,0,0,0};
+            p = pData;
+            for (i = 0; i < count; i++)
+            {
+                if (!func(&sizestream, field, p))
+                    return false;
+                p = (const char*)p + field->data_size;
+            }
+            size = sizestream.bytes_written;
+        }
+        
+        if (!pb_encode_varint(stream, (uint64_t)size))
+            return false;
+        
+        if (stream->callback == NULL)
+            return pb_write(stream, NULL, size); /* Just sizing.. */
+        
+        /* Write the data */
+        p = pData;
+        for (i = 0; i < count; i++)
+        {
+            if (!func(stream, field, p))
+                return false;
+            p = (const char*)p + field->data_size;
+        }
+    }
+    else
+    {
+        p = pData;
+        for (i = 0; i < count; i++)
+        {
+            if (!pb_encode_tag_for_field(stream, field))
+                return false;
+            if (!func(stream, field, p))
+                return false;
+            p = (const char*)p + field->data_size;
+        }
+    }
+    
+    return true;
+}
+
+bool checkreturn pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
+{
+    const pb_field_t *field = fields;
+    const void *pData = src_struct;
+    const void *pSize;
+    size_t prev_size = 0;
+    
+    while (field->tag != 0)
+    {
+        pb_encoder_t func = PB_ENCODERS[PB_LTYPE(field->type)];
+        pData = (const char*)pData + prev_size + field->data_offset;
+        pSize = (const char*)pData + field->size_offset;
+        
+        prev_size = field->data_size;
+        if (PB_HTYPE(field->type) == PB_HTYPE_ARRAY)
+            prev_size *= field->array_size;
+                
+        switch (PB_HTYPE(field->type))
+        {
+            case PB_HTYPE_REQUIRED:
+                if (!pb_encode_tag_for_field(stream, field))
+                    return false;
+                if (!func(stream, field, pData))
+                    return false;
+                break;
+            
+            case PB_HTYPE_OPTIONAL:
+                if (*(const bool*)pSize)
+                {
+                    if (!pb_encode_tag_for_field(stream, field))
+                        return false;
+                
+                    if (!func(stream, field, pData))
+                        return false;
+                }
+                break;
+            
+            case PB_HTYPE_ARRAY:
+                if (!encode_array(stream, field, pData, *(const size_t*)pSize, func))
+                    return false;
+                break;
+            
+            case PB_HTYPE_CALLBACK:
+            {
+                const pb_callback_t *callback = (const pb_callback_t*)pData;
+                if (callback->funcs.encode != NULL)
+                {
+                    if (!callback->funcs.encode(stream, field, callback->arg))
+                        return false;
+                }
+                break;
+            }
+        }
+    
+        field++;
+    }
+    
+    return true;
+}
+
+/* Helper functions */
+bool checkreturn pb_encode_varint(pb_ostream_t *stream, uint64_t value)
+{
+    uint8_t buffer[10];
+    size_t i = 0;
+    
+    if (value == 0)
+        return pb_write(stream, (uint8_t*)&value, 1);
+    
+    while (value)
+    {
+        buffer[i] = (uint8_t)((value & 0x7F) | 0x80);
+        value >>= 7;
+        i++;
+    }
+    buffer[i-1] &= 0x7F; /* Unset top bit on last byte */
+    
+    return pb_write(stream, buffer, i);
+}
+
+bool checkreturn pb_encode_svarint(pb_ostream_t *stream, int64_t value)
+{
+    uint64_t zigzagged;
+    if (value < 0)
+        zigzagged = (uint64_t)(~(value << 1));
+    else
+        zigzagged = (uint64_t)(value << 1);
+    
+    return pb_encode_varint(stream, zigzagged);
+}
+
+bool checkreturn pb_encode_fixed32(pb_ostream_t *stream, const void *value)
+{
+    #ifdef __BIG_ENDIAN__
+    const uint8_t *bytes = value;
+    uint8_t lebytes[4];
+    lebytes[0] = bytes[3];
+    lebytes[1] = bytes[2];
+    lebytes[2] = bytes[1];
+    lebytes[3] = bytes[0];
+    return pb_write(stream, lebytes, 4);
+    #else
+    return pb_write(stream, (const uint8_t*)value, 4);
+    #endif
+}
+
+bool checkreturn pb_encode_fixed64(pb_ostream_t *stream, const void *value)
+{
+    #ifdef __BIG_ENDIAN__
+    const uint8_t *bytes = value;
+    uint8_t lebytes[8];
+    lebytes[0] = bytes[7];
+    lebytes[1] = bytes[6];
+    lebytes[2] = bytes[5];
+    lebytes[3] = bytes[4];
+    lebytes[4] = bytes[3];
+    lebytes[5] = bytes[2];
+    lebytes[6] = bytes[1];
+    lebytes[7] = bytes[0];
+    return pb_write(stream, lebytes, 8);
+    #else
+    return pb_write(stream, (const uint8_t*)value, 8);
+    #endif
+}
+
+bool checkreturn pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number)
+{
+    uint64_t tag = wiretype | (field_number << 3);
+    return pb_encode_varint(stream, tag);
+}
+
+bool checkreturn pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field)
+{
+    pb_wire_type_t wiretype;
+    switch (PB_LTYPE(field->type))
+    {
+        case PB_LTYPE_VARINT:
+        case PB_LTYPE_SVARINT:
+            wiretype = PB_WT_VARINT;
+            break;
+        
+        case PB_LTYPE_FIXED32:
+            wiretype = PB_WT_32BIT;
+            break;
+        
+        case PB_LTYPE_FIXED64:
+            wiretype = PB_WT_64BIT;
+            break;
+        
+        case PB_LTYPE_BYTES:
+        case PB_LTYPE_STRING:
+        case PB_LTYPE_SUBMESSAGE:
+            wiretype = PB_WT_STRING;
+            break;
+        
+        default:
+            return false;
+    }
+    
+    return pb_encode_tag(stream, wiretype, field->tag);
+}
+
+bool checkreturn pb_encode_string(pb_ostream_t *stream, const uint8_t *buffer, size_t size)
+{
+    if (!pb_encode_varint(stream, (uint64_t)size))
+        return false;
+    
+    return pb_write(stream, buffer, size);
+}
+
+bool checkreturn pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
+{
+    /* First calculate the message size using a non-writing substream. */
+    pb_ostream_t substream = {0,0,0,0};
+    size_t size;
+    bool status;
+    
+    if (!pb_encode(&substream, fields, src_struct))
+        return false;
+    
+    size = substream.bytes_written;
+    
+    if (!pb_encode_varint(stream, (uint64_t)size))
+        return false;
+    
+    if (stream->callback == NULL)
+        return pb_write(stream, NULL, size); /* Just sizing */
+    
+    if (stream->bytes_written + size > stream->max_size)
+        return false;
+        
+    /* Use a substream to verify that a callback doesn't write more than
+     * what it did the first time. */
+    substream.callback = stream->callback;
+    substream.state = stream->state;
+    substream.max_size = size;
+    substream.bytes_written = 0;
+    
+    status = pb_encode(&substream, fields, src_struct);
+    
+    stream->bytes_written += substream.bytes_written;
+    stream->state = substream.state;
+    
+    if (substream.bytes_written != size)
+        return false;
+    
+    return status;
+}
+
+/* Field encoders */
+
+bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
+{
+    uint64_t value = 0;
+    
+    switch (field->data_size)
+    {
+        case 1: value = *(const uint8_t*)src; break;
+        case 2: value = *(const uint16_t*)src; break;
+        case 4: value = *(const uint32_t*)src; break;
+        case 8: value = *(const uint64_t*)src; break;
+        default: return false;
+    }
+    
+    return pb_encode_varint(stream, value);
+}
+
+bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
+{
+    int64_t value = 0;
+    
+    switch (field->data_size)
+    {
+        case 4: value = *(const int32_t*)src; break;
+        case 8: value = *(const int64_t*)src; break;
+        default: return false;
+    }
+    
+    return pb_encode_svarint(stream, value);
+}
+
+bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src)
+{
+    UNUSED(field);
+    return pb_encode_fixed64(stream, src);
+}
+
+bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src)
+{
+    UNUSED(field);
+    return pb_encode_fixed32(stream, src);
+}
+
+bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src)
+{
+    const pb_bytes_array_t *bytes = (const pb_bytes_array_t*)src;
+    UNUSED(field);
+    return pb_encode_string(stream, bytes->bytes, bytes->size);
+}
+
+bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src)
+{
+    UNUSED(field);
+    return pb_encode_string(stream, (const uint8_t*)src, strlen((const char*)src));
+}
+
+bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src)
+{
+    if (field->ptr == NULL)
+        return false;
+    
+    return pb_encode_submessage(stream, (const pb_field_t*)field->ptr, src);
+}
+