Improvements, array support

git-svn-id: https://svn.kapsi.fi/jpa/nanopb@943 e3a754e5-d11d-0410-8d38-ebb782a927b9

4 files changed, 455 insertions, 194 deletions

diff --git a/pb.h b/pb.h
index 2cae75c5..99e4bf7e 100644
--- a/pb.h
+++ b/pb.h
@@ -3,19 +3,36 @@
 
 #include <stdint.h>
 #include <stddef.h> // size_t
+#include <stdbool.h>
+
+#ifdef __GNUC__
+// This just reduces memory requirements, but is not required.
+#define pb_packed __attribute__((packed))
+#else
+#define pb_packed
+#endif
 
 /* Lightweight input stream.
- * If buf is NULL, read but don't store bytes. */
+ * If buf is NULL, read but don't store bytes.
+ * You have to provide a callback function for reading.
+ * You can use state to store your own data (e.g. buffer pointer),
+ * and rely on pb_read to verify that no-body reads past bytes_left.
+ * However, substreams may change bytes_left so don't use that to
+ * compute any pointers.
+ */
 typedef struct _pb_istream_t pb_istream_t;
 struct _pb_istream_t
 {
-    bool (*callback)(pb_istream_t *stream, char *buf, size_t count);
+    bool (*callback)(pb_istream_t *stream, uint8_t *buf, size_t count);
     void *state; // Free field for use by callback implementation
     size_t bytes_left;
 };
 
-static inline bool pb_read(pb_istream_t *stream, char *buf, size_t count)
+static inline bool pb_read(pb_istream_t *stream, uint8_t *buf, size_t count)
 {
+    if (stream->bytes_left < count)
+        return false;
+    
     bool status = stream->callback(stream, buf, count);
     stream->bytes_left -= count;
     return status;
@@ -25,74 +42,129 @@ static inline bool pb_read(pb_istream_t *stream, char *buf, size_t count)
 typedef struct _pb_ostream_t pb_ostream_t;
 struct _pb_ostream_t
 {
-    bool (*callback)(pb_ostream_t *stream, const char *buf, size_t count);
+    bool (*callback)(pb_ostream_t *stream, const uint8_t *buf, size_t count);
     void *state; // Free field for use by callback implementation
     size_t bytes_written;
 };
 
-static inline bool pb_write(pb_ostream_t *stream, const char *buf, size_t count)
+static inline bool pb_write(pb_ostream_t *stream, const uint8_t *buf, size_t count)
 {
     bool status = stream->callback(stream, buf, count);
     stream->bytes_written += count;
     return status;
 }
 
-/* List of possible decode/encode action types */
+/* List of possible field types
+ * Least-significant 4 bits tell the scalar type
+ * Most-significant 4 bits specify repeated/required/packed etc.
+ * 
+ * INT32 and UINT32 are treated the same, as are (U)INT64 and (S)FIXED*
+ * These types are simply casted to correct field type when they are
+ * assigned to the memory pointer.
+ * SINT* is different, though, because it is zig-zag coded.
+ */
 
 typedef enum {
-    // Special case. Sets boolean field to true, continues parsing the data.
-    PB_ACT_HAS,
-    
     // Standard integer types
-    PB_ACT_UINT32,
-    PB_ACT_SINT32,
-    PB_ACT_INT32,
-    PB_ACT_FIXED32,
-    PB_ACT_SFIXED32,
-    PB_ACT_UINT64,
-    PB_ACT_SINT64,
-    PB_ACT_INT64,
-    PB_ACT_FIXED64,
-    PB_ACT_SFIXED64,
-    PB_ACT_BOOL,
+    PB_LTYPE_UINT32 = 0x00,
+    PB_LTYPE_INT32 = 0x00,
+    PB_LTYPE_SINT32 = 0x01,
+    PB_LTYPE_FIXED32 = 0x02,
+    PB_LTYPE_SFIXED32 = 0x02,
+    PB_LTYPE_UINT64 = 0x03,
+    PB_LTYPE_INT64 = 0x03,
+    PB_LTYPE_SINT64 = 0x04,
+    PB_LTYPE_FIXED64 = 0x05,
+    PB_LTYPE_SFIXED64 = 0x05,
+    PB_LTYPE_BOOL = 0x06,
+    PB_LTYPE_ENUM = 0x07,
     
     // Standard float types
-    PB_ACT_FLOAT,
-    PB_ACT_DOUBLE,
+    PB_LTYPE_FLOAT = 0x08,
+    PB_LTYPE_DOUBLE = 0x09,
+    
+    // Byte array with pre-allocated buffer.
+    // data_size is the length of the allocated PB_BYTES_ARRAY structure.
+    PB_LTYPE_BYTES = 0x0A,
+    
+    // String with pre-allocated buffer.
+    // data_size is the maximum length.
+    PB_LTYPE_STRING = 0x0B,
     
-    // Constant-sized array
-    PB_ACT_BYTES,
+    // Submessage
+    // submsg_fields is pointer to field descriptions
+    PB_LTYPE_SUBMESSAGE = 0x0C,
     
-    // Constant-sized array, with null termination
-    PB_ACT_STRING,
+    /////////////
+    // Modifier flags
     
-    // Callback function pointer in field value
-    PB_ACT_SUBMESSAGE,
+    // Just the basic, write data at data_offset
+    PB_HTYPE_REQUIRED = 0x00,
     
-    PB_LAST_ACT
-} pb_action_t;
+    // Write true at size_offset
+    PB_HTYPE_OPTIONAL = 0x10,
+    
+    // Read to pre-allocated array
+    // Maximum number of entries is array_size,
+    // actual number is stored at size_offset
+    PB_HTYPE_ARRAY = 0x20,
+    
+    // Works for all required/optional/repeated fields.
+    // data_offset points to pb_callback_t structure.
+    // LTYPE is ignored.
+    PB_HTYPE_CALLBACK = 0x30
+} pb_packed pb_type_t;
 
-// This structure is used in constants to specify struct fields.
-typedef struct {
-    int field_number;
-    uint16_t offset;
-    pb_action_t action;
-    uint8_t fieldsize;
-} pb_field_t;
+#define PB_HTYPE(x) ((x) & 0xF0)
+#define PB_LTYPE(x) ((x) & 0x0F)
+
+/* This structure is used in auto-generated constants
+ * to specify struct fields.
+ * You can change field sizes here if you need structures
+ * larger than 256 bytes or field tags larger than 256.
+ * The compiler should complain if your .proto has such
+ * structures ("initializer too large for type").
+ */
+typedef struct _pb_field_t pb_field_t;
+struct _pb_field_t {
+    uint8_t tag;
+    pb_type_t type;
+    uint8_t data_offset; // Offset of actual data or array start
+    uint8_t size_offset; // Offset of array size or has-boolean
+    uint8_t data_size; // Data size in bytes for a single item
+    uint8_t array_size; // Maximum number of entries in array
+    
+    // Field definitions for submessage
+    // OR default value for all other non-array, non-callback types
+    // If null, then field will zeroed.
+    const void *ptr;
+} pb_packed;
 
 #define PB_LAST_FIELD {0,0,0,0}
 
-/* --- Types to use inside generated structures. --- */
+// This structure is used for 'bytes' arrays.
+// It has the number of bytes in the beginning, and after that an array.
+#define PB_BYTES_ARRAY(buffersize) \
+struct { \
+    size_t size; \
+    uint8_t bytes[buffersize]; \
+}
 
-// Byte array and size word.
-// Note: because of variable length array, this type cannot be directly used.
-// Autogenerated code declares the same type of fields but with explicit length.
-typedef struct {
-    size_t size;
-    char bytes[];
-} pb_bytearray_t;
+typedef PB_BYTES_ARRAY(1) pb_bytes_array_t;
 
 // This structure is used for giving the callback function.
+//
+// The decoding callback will be given a limited-length stream
+// If the wire type was string, the length is the length of the string.
+// If the wire type was a varint/fixed32/fixed64, the length is the length
+// of the actual value.
+// The function may be called multiple times (especially for repeated types,
+// but also otherwise if the message happens to contain the field multiple
+// times.)
+//
+// The encoding callback will receive the actual output stream.
+// It should write all the data in one call, including the field tag and
+// wire type. It can write multiple fields.
 typedef struct _pb_callback_t pb_callback_t;
 struct _pb_callback_t {
     union {
diff --git a/pb_decode.c b/pb_decode.c
index 884cf18e..acd9b204 100644
--- a/pb_decode.c
+++ b/pb_decode.c
@@ -1,61 +1,63 @@
-/* pb_decode.c -- decode a protobuf using callback functions
+/* pb_decode.c -- decode a protobuf using minimal resources
  *
  * 2011 Petteri Aimonen <jpa@kapsi.fi>
  */
 
+#include "pb.h"
 #include "pb_decode.h"
+#include <string.h>
 
-const pb_decoder_t PB_DECODERS[PB_LAST_ACT] = {
-    NULL,
+const pb_decoder_t PB_DECODERS[16] = {
     &pb_dec_uint32,
     &pb_dec_sint32,
-    &pb_dec_uint32, // Cast to int32
     &pb_dec_fixed32,
-    &pb_dec_fixed32, // Cast to int32
     &pb_dec_uint64,
     &pb_dec_sint64,
-    &pb_dec_uint64, // Cast to int64
     &pb_dec_fixed64,
-    &pb_dec_fixed64, // Cast to int64
     &pb_dec_bool,
+    &pb_dec_enum,
+    
     &pb_dec_float,
     &pb_dec_double,
+    
     &pb_dec_bytes,
     &pb_dec_string,
     &pb_dec_submessage
 };
 
-enum wire_type {
-    WT_VARINT = 0,
-    WT_64BIT  = 1,
-    WT_STRING = 2,
-    WT_32BIT  = 5
-};
+////////////////////////
+// Helper functions
+////////////////////////
 
-// Note: pb_decode_varint32 is a bit un-orthodox:
-// it will refuse to decode values that exceed uint32 range.
-// The Google implementation would simply cast to 32 bits.
-bool pb_decode_varint32(pb_istream_t *stream, uint32_t *dest)
+static bool buf_read(pb_istream_t *stream, uint8_t *buf, size_t count)
 {
-    char byte;
-    int bitpos = 0;
-    *dest = 0;
+    uint8_t *source = (uint8_t*)stream->state;
     
-    while (bitpos < 32 && pb_read(stream, &byte, 1))
-    {
-        *dest |= (byte & 0x7F) << bitpos;
-        bitpos += 7;
-        
-        if (!(byte & 0x80))
-            return true;
-    }
+    if (buf != NULL)
+        memcpy(buf, source, count);
     
-    return false;
+    stream->state = source + count;
+    return true;
+}
+
+pb_istream_t pb_istream_from_buffer(uint8_t *buf, size_t bufsize)
+{
+    pb_istream_t stream = {&buf_read, buf, bufsize};
+    return stream;
+}
+
+bool pb_decode_varint32(pb_istream_t *stream, uint32_t *dest)
+{
+    uint64_t temp;
+    if (!pb_decode_varint64(stream, &temp))
+        return false;
+    *dest = temp;
+    return true;
 }
 
 bool pb_decode_varint64(pb_istream_t *stream, uint64_t *dest)
 {
-    char byte;
+    uint8_t byte;
     int bitpos = 0;
     *dest = 0;
     
@@ -73,7 +75,7 @@ bool pb_decode_varint64(pb_istream_t *stream, uint64_t *dest)
 
 bool pb_skip_varint(pb_istream_t *stream)
 {
-    char byte;
+    uint8_t byte;
     do
     {
         if (!pb_read(stream, &byte, 1))
@@ -91,72 +93,235 @@ bool pb_skip_string(pb_istream_t *stream)
     return pb_read(stream, NULL, length);
 }
 
-bool pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest)
+/* Currently all wire type related stuff is kept hidden from
+ * callbacks. They shouldn't need it. It's better for performance
+ * to just assume the correct type and fail safely on corrupt message.
+ */
+
+enum wire_type_t {
+    WT_VARINT = 0,
+    WT_64BIT  = 1,
+    WT_STRING = 2,
+    WT_32BIT  = 5
+};
+
+static bool skip(pb_istream_t *stream, int wire_type)
 {
-    while (stream->bytes_left)
+    switch (wire_type)
     {
-        uint32_t temp;
-        if (!pb_decode_varint32(stream, &temp))
-            return false;
+        case WT_VARINT: return pb_skip_varint(stream);
+        case WT_64BIT: return pb_read(stream, NULL, 8);
+        case WT_STRING: return pb_skip_string(stream);
+        case WT_32BIT: return pb_read(stream, NULL, 4);
+        default: return false;
+    }
+}
+
+// Read a raw value to buffer, for the purpose of passing it to callback.
+// Size is maximum size on call, and actual size on return.
+static bool read_raw_value(pb_istream_t *stream, int wire_type, uint8_t *buf, size_t *size)
+{
+    size_t max_size = *size;
+    switch (wire_type)
+    {
+        case WT_VARINT:
+            *size = 0;
+            do
+            {
+                (*size)++;
+                if (*size > max_size) return false;
+                if (!pb_read(stream, buf++, 1)) return false;
+            } while (*buf & 0x80);
+            return true;
+            
+        case WT_64BIT:
+            *size = 8;
+            return pb_read(stream, buf, 8);
         
-        int field_number = temp >> 3;
-        int wire_type = temp & 7;
+        case WT_32BIT:
+            *size = 4;
+            return pb_read(stream, buf, 4);
         
-        const pb_field_t *field = fields;
-        while (field->field_number != 0)
-        {
-            if (field->field_number != field_number)
+        default: return false;
+    }
+}
+
+// Decode string length from stream and return a substream with limited length
+static bool make_string_substream(pb_istream_t *stream, pb_istream_t *substream)
+{
+    uint32_t size;
+    if (!pb_decode_varint32(stream, &size))
+        return false;
+    
+    *substream = *stream;
+    if (substream->bytes_left < size)
+        return false;
+    
+    substream->bytes_left = size;
+    stream->bytes_left -= size;
+    return true;
+}
+
+bool decode_field(pb_istream_t *stream, int wire_type, const pb_field_t *field, void *dest_struct)
+{
+    pb_decoder_t func = PB_DECODERS[PB_LTYPE(field->type)];
+    void *pData = (char*)dest_struct + field->data_offset;
+    void *pSize = (char*)dest_struct + field->size_offset;
+    
+    switch (PB_HTYPE(field->type))
+    {
+        case PB_HTYPE_REQUIRED:
+            return func(stream, field, pData);
+            
+        case PB_HTYPE_OPTIONAL:
+            *(bool*)pSize = true;
+            return func(stream, field, pData);
+    
+        case PB_HTYPE_ARRAY:
+            if (wire_type == WT_STRING
+                && PB_LTYPE(field->type) != PB_LTYPE_BYTES
+                && PB_LTYPE(field->type) != PB_LTYPE_STRING
+                && PB_LTYPE(field->type) != PB_LTYPE_SUBMESSAGE)
             {
-                field++;
-                continue;
+                // Packed array
+                size_t *size = (size_t*)pSize;
+                pb_istream_t substream;
+                if (!make_string_substream(stream, &substream))
+                    return false;
+                
+                while (substream.bytes_left && *size < field->array_size)
+                {
+                    void *pItem = pData + field->data_size * (*size);
+                    if (!func(stream, field, pItem))
+                        return false;
+                    (*size)++;
+                }
+                return (substream.bytes_left == 0);
             }
-            
-            void *destfield = dest + field->offset; 
-            
-            if (field->action == PB_ACT_HAS)
+            else
             {
-                *(bool*)destfield = true;
-                field++;
-                continue;
+                // Repeated field
+                size_t *size = (size_t*)pSize;
+                if (*size >= field->array_size)
+                    return false;
+                
+                void *pItem = pData + field->data_size * (*size);
+                (*size)++;
+                return func(stream, field, pItem);
             }
-            
-            pb_decoder_t func = PB_DECODERS[field->action];
-            if (!func(stream, field, destfield))
-                return false;
-            
-            break;
-        }
         
-        if (field->field_number == 0) // No match found, skip data
-        {
-            bool status = false;
-            switch (wire_type)
+        case PB_HTYPE_CALLBACK:
+            if (wire_type == WT_STRING)
             {
-                case WT_VARINT:
-                    status = pb_skip_varint(stream);
-                    break;
+                pb_callback_t *pCallback = (pb_callback_t*)pData;
+                pb_istream_t substream;
                 
-                case WT_64BIT:
-                    status = pb_read(stream, NULL, 8);
-                    break;
+                if (!make_string_substream(stream, &substream))
+                    return false;
                 
-                case WT_STRING:
-                    status = pb_skip_string(stream);
-                    break;
+                while (substream.bytes_left)
+                {
+                    if (!pCallback->funcs.decode(&substream, field, pCallback->arg))
+                        return false;
+                }
+            }
+            else
+            {
+                // Copy the single scalar value to stack.
+                // This is required so that we can limit the stream length,
+                // which in turn allows to use same callback for packed and
+                // not-packed fields.
+                uint8_t buffer[10];
+                size_t size = sizeof(buffer);
+                if (!read_raw_value(stream, wire_type, buffer, &size))
+                    return false;
+                pb_istream_t substream = pb_istream_from_buffer(buffer, size);
                 
-                case WT_32BIT:
-                    status = pb_read(stream, NULL, 4);
-                    break;
+                pb_callback_t *pCallback = (pb_callback_t*)pData;
+                return pCallback->funcs.decode(&substream, field, pCallback->arg);
             }
             
-            if (!status)
-                return false;
+        default:
+            return false;
+    }
+}
+
+bool pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
+{
+    // Used to check for required fields
+    uint32_t fields_seen = 0;
+    int i;
+    
+    // Initialize size/has fields and apply default values
+    for (i = 0; fields[i].tag != 0; i++)
+    {
+        void *pData = (char*)dest_struct + fields[i].data_offset;
+        void *pSize = (char*)dest_struct + fields[i].size_offset;
+        if (PB_HTYPE(fields[i].type) == PB_HTYPE_OPTIONAL)
+        {
+            *(bool*)pSize = false;
+        }
+        else if (PB_HTYPE(fields[i].type) == PB_HTYPE_ARRAY)
+        {
+            *(size_t*)pSize = 0;
+        }
+        
+        if (PB_HTYPE(fields[i].type) != PB_HTYPE_ARRAY &&
+            PB_HTYPE(fields[i].type) != PB_HTYPE_CALLBACK)
+        {
+            if (fields[i].ptr != NULL)
+            {
+                memcpy(pData, fields[i].ptr, fields[i].data_size);
+            }
+            else
+            {
+                memset(pData, 0, fields[i].data_size);
+            }
+        }
+    }
+    
+    while (stream->bytes_left)
+    {
+        uint32_t temp;
+        if (!pb_decode_varint32(stream, &temp))
+            return false;
+        
+        int tag = temp >> 3;
+        int wire_type = temp & 7;
+        
+        i = 0;
+        while (fields[i].tag != 0 && fields[i].tag != tag)
+        {
+            i++;
+        }
+        
+        if (fields[i].tag == 0) // No match found, skip data
+        {
+            skip(stream, wire_type);
+            continue;
+        }
+        
+        fields_seen |= 1 << (i & 31);
+            
+        if (!decode_field(stream, wire_type, &fields[i], dest_struct))
+            return false;
+    }
+    
+    // Check that all required fields (mod 31) were present.
+    for (i = 0; fields[i].tag != 0; i++)
+    {
+        if (PB_HTYPE(fields[i].type) == PB_HTYPE_REQUIRED &&
+            !(fields_seen & (1 << (i & 31))))
+        {
+            return false;
         }
     }
     
     return true;
 }
 
+/* Field decoders */
+
 bool pb_dec_uint32(pb_istream_t *stream, const pb_field_t *field, void *dest)
 {
     return pb_decode_varint32(stream, (uint32_t*)dest);
@@ -172,11 +337,15 @@ bool pb_dec_sint32(pb_istream_t *stream, const pb_field_t *field, void *dest)
 
 bool pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest)
 {
-    char bytes[4] = {0};
+    uint8_t bytes[4] = {0};
     bool status = pb_read(stream, bytes, 4);
-    *(uint32_t*)dest = 
-        bytes[0] | ((uint32_t)bytes[1] << 8) |
-        ((uint32_t)bytes[2] << 16) | ((uint32_t)bytes[3] << 24);
+    
+#ifdef __BIG_ENDIAN__
+    uint8_t lebytes[4] = {bytes[3], bytes[2], bytes[1], bytes[0]};
+    memcpy(dest, lebytes, 4);
+#else
+    memcpy(dest, bytes, 4);
+#endif
     return status;
 }
 
@@ -195,13 +364,16 @@ bool pb_dec_sint64(pb_istream_t *stream, const pb_field_t *field, void *dest)
 
 bool pb_dec_fixed64(pb_istream_t *stream, const pb_field_t *field, void *dest)
 {
-    char bytes[8] = {0};
+    uint8_t bytes[8] = {0};
     bool status = pb_read(stream, bytes, 8);
-    *(uint64_t*)dest =
-        (uint64_t)bytes[0] | ((uint64_t)bytes[1] << 8) |
-        ((uint64_t)bytes[2] << 16) | ((uint64_t)bytes[3] << 24) |
-        ((uint64_t)bytes[4] << 32) | ((uint64_t)bytes[5] << 40) |
-        ((uint64_t)bytes[6] << 48) | ((uint64_t)bytes[7] << 56);
+    
+#ifdef __BIG_ENDIAN__
+    uint8_t lebytes[8] = {bytes[7], bytes[6], bytes[5], bytes[4], 
+                          bytes[3], bytes[2], bytes[1], bytes[0]};
+    memcpy(dest, lebytes, 4);
+#else
+    memcpy(dest, bytes, 4);
+#endif
     return status;
 }
 
@@ -213,25 +385,37 @@ bool pb_dec_bool(pb_istream_t *stream, const pb_field_t *field, void *dest)
     return status;
 }
 
+bool pb_dec_enum(pb_istream_t *stream, const pb_field_t *field, void *dest)
+{
+    // Enum sizes can vary, copy only data_size amount of bytes.
+    uint32_t temp = 0;
+    bool status = pb_decode_varint32(stream, &temp);
+    memcpy(dest, &temp, field->data_size);
+    return status;
+}
+
 bool pb_dec_float(pb_istream_t *stream, const pb_field_t *field, void *dest)
 {
-    return pb_read(stream, (char*)dest, sizeof(float));
+    return pb_read(stream, (uint8_t*)dest, sizeof(float));
 }
 
 bool pb_dec_double(pb_istream_t *stream, const pb_field_t *field, void *dest)
 {
-    return pb_read(stream, (char*)dest, sizeof(double));
+    return pb_read(stream, (uint8_t*)dest, sizeof(double));
 }
 
 bool pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, void *dest)
 {
-    pb_bytearray_t *x = (pb_bytearray_t*)dest;
+    pb_bytes_array_t *x = (pb_bytes_array_t*)dest;
+    
     uint32_t temp;
     if (!pb_decode_varint32(stream, &temp))
         return false;
     x->size = temp;
     
-    if (x->size > field->fieldsize)
+    // Note: data_size includes the size of the x.size field, too.
+    // Calculate actual size starting from offset.
+    if (x->size > field->data_size - offsetof(pb_bytes_array_t, bytes))
         return false;
     
     return pb_read(stream, x->bytes, x->size);
@@ -243,32 +427,23 @@ bool pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest)
     if (!pb_decode_varint32(stream, &size))
         return false;
     
-    if (size > field->fieldsize - 1)
+    if (size > field->data_size - 1)
         return false;
     
-    bool status = pb_read(stream, (char*)dest, size);
-    *((char*)dest + size) = 0;
+    bool status = pb_read(stream, (uint8_t*)dest, size);
+    *((uint8_t*)dest + size) = 0;
     return status;
 }
 
 bool pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest)
 {
-    pb_callback_t *x = (pb_callback_t*)dest;
+    pb_istream_t substream;
     
-    if (x->funcs.decode == NULL)
-        return pb_skip_string(stream);
-    
-    uint32_t size;
-    if (!pb_decode_varint32(stream, &size))
+    if (!make_string_substream(stream, &substream))
         return false;
     
-    if (stream->bytes_left < size)
+    if (field->ptr == NULL)
         return false;
     
-    // Make a limited-length istream for decoding submessage
-    pb_istream_t shortstream = *stream;
-    shortstream.bytes_left = size;
-    bool status = x->funcs.decode(&shortstream, field, x->arg);
-    stream->bytes_left -= size - shortstream.bytes_left;
-    return status;
+    return pb_decode(&substream, (pb_field_t*)field->ptr, dest);
 }
diff --git a/pb_decode.h b/pb_decode.h
index b71e20b1..2f689394 100644
--- a/pb_decode.h
+++ b/pb_decode.h
@@ -6,12 +6,14 @@
 
 // Decode from stream to destination struct.
 // The actual struct pointed to by dest must match the description in fields.
-bool pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest);
+bool pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct);
 
 /* --- Helper functions ---
- * You may want to use these from your callbacks.
+ * You may want to use these from your caller or callbacks.
  */
 
+pb_istream_t pb_istream_from_buffer(uint8_t *buf, size_t bufsize);
+
 bool pb_decode_varint32(pb_istream_t *stream, uint32_t *dest);
 bool pb_decode_varint64(pb_istream_t *stream, uint64_t *dest);
 
@@ -20,10 +22,10 @@ bool pb_skip_string(pb_istream_t *stream);
 
 /* --- Field decoders ---
  * Each decoder takes stream and field description, and a pointer to the field
- * in the destination struct (dest = struct_addr + field->offset).
+ * in the destination struct (dest = struct_addr + field->data_offset).
+ * For arrays, these functions are called repeatedly.
  */
 
-// Integer types.
 bool pb_dec_uint32(pb_istream_t *stream, const pb_field_t *field, void *dest);
 bool pb_dec_sint32(pb_istream_t *stream, const pb_field_t *field, void *dest);
 bool pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest);
@@ -31,25 +33,20 @@ bool pb_dec_uint64(pb_istream_t *stream, const pb_field_t *field, void *dest);
 bool pb_dec_sint64(pb_istream_t *stream, const pb_field_t *field, void *dest);
 bool pb_dec_fixed64(pb_istream_t *stream, const pb_field_t *field, void *dest);
 bool pb_dec_bool(pb_istream_t *stream, const pb_field_t *field, void *dest);
+bool pb_dec_enum(pb_istream_t *stream, const pb_field_t *field, void *dest);
 
-// Floating point types. Info is ignored.
 bool pb_dec_float(pb_istream_t *stream, const pb_field_t *field, void *dest);
 bool pb_dec_double(pb_istream_t *stream, const pb_field_t *field, void *dest);
 
-// Byte array. Dest is pointer to 
 bool pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, void *dest);
-
-// Null-terminated string.
 bool pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest);
-
-// Use callback. Dest is pointer to pb_callback_t struct.
 bool pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest);
 
 typedef bool (*pb_decoder_t)(pb_istream_t *stream, const pb_field_t *field, void *dest);
 
 /* --- Function pointers to field decoders ---
- * Order in the array must match pb_action_t numbering.
+ * Order in the array must match pb_action_t LTYPE numbering.
  */
-const pb_decoder_t PB_DECODERS[PB_LAST_ACT];
+const pb_decoder_t PB_DECODERS[16];
 
 #endif
diff --git a/tests/test_decode1.c b/tests/test_decode1.c
index dc0831a2..fbdb7db6 100644
--- a/tests/test_decode1.c
+++ b/tests/test_decode1.c
@@ -9,8 +9,6 @@ typedef enum {
     Person_PhoneType_MOBILE = 0,
     Person_PhoneType_HOME = 1,
     Person_PhoneType_WORK = 2,
-    
-    _Person_PhoneType_size = 0xFFFFFFFF // Force 32-bit enum
 } Person_PhoneType;
 
 typedef struct {
@@ -24,52 +22,71 @@ typedef struct {
     int32_t id;
     bool has_email;
     char email[40];
-
-    pb_callback_t phone;
+    size_t phone_size;
+    Person_PhoneNumber phone[5];
 } Person;
 
 /* Field descriptions */
 #define membersize(st, m) (sizeof ((st*)0)->m)
 
+const Person_PhoneType Person_PhoneType_type_default = Person_PhoneType_HOME;
+
 const pb_field_t Person_PhoneNumber_fields[] = {
-    {1, offsetof(Person_PhoneNumber, number), PB_ACT_STRING, membersize(Person_PhoneNumber, number)},
-    {2, offsetof(Person_PhoneNumber, has_type), PB_ACT_HAS, membersize(Person_PhoneNumber, has_type)},
-    {2, offsetof(Person_PhoneNumber, type), PB_ACT_UINT32, membersize(Person_PhoneNumber, type)},
+    {1, PB_HTYPE_REQUIRED | PB_LTYPE_STRING,
+        offsetof(Person_PhoneNumber, number), 0,
+        membersize(Person_PhoneNumber, number), 0, 0},
+        
+    {2, PB_HTYPE_OPTIONAL | PB_LTYPE_ENUM,
+        offsetof(Person_PhoneNumber, type),
+        offsetof(Person_PhoneNumber, has_type),
+        membersize(Person_PhoneNumber, type), 0,
+        &Person_PhoneType_type_default},
+    
     PB_LAST_FIELD
 };
 
 const pb_field_t Person_fields[] = {
-    {1, offsetof(Person, name), PB_ACT_STRING, membersize(Person, name)},
-    {2, offsetof(Person, id), PB_ACT_INT32, membersize(Person, id)},
-    {3, offsetof(Person, email), PB_ACT_STRING, membersize(Person, email)},
-    {4, offsetof(Person, phone), PB_ACT_SUBMESSAGE, membersize(Person, phone)}
+    {1, PB_HTYPE_REQUIRED | PB_LTYPE_STRING,
+        offsetof(Person, name), 0,
+        membersize(Person, name), 0, 0},
+    
+    {2, PB_HTYPE_REQUIRED | PB_LTYPE_INT32,
+        offsetof(Person, id), 0,
+        membersize(Person, id), 0, 0},
+    
+    {3, PB_HTYPE_OPTIONAL | PB_LTYPE_STRING,
+        offsetof(Person, email),
+        offsetof(Person, has_email),
+        membersize(Person, email), 0, 0},
+    
+    {4, PB_HTYPE_ARRAY | PB_LTYPE_SUBMESSAGE,
+        offsetof(Person, phone),
+        offsetof(Person, phone_size),
+        membersize(Person, phone[0]),
+        membersize(Person, phone) / membersize(Person, phone[0]),
+        Person_PhoneNumber_fields},
+    
+    PB_LAST_FIELD
 };
 
-/* Default value descriptions */
-#define Person_PhoneNumber_default {"", false, Person_PhoneType_HOME};
-#define Person_default {"", 0, false, "", {{0},0}};
-
 /* And now, the actual test program */
 
-bool print_phonenumber(pb_istream_t *stream, const pb_field_t *field, void *arg)
-{
-    Person_PhoneNumber x = Person_PhoneNumber_default;
-    if (!pb_decode(stream, Person_PhoneNumber_fields, &x))
-        return false;
-    
-    printf("PhoneNumber: number '%s' type '%d'\n", x.number, x.type);
-    return true;
-}
-
 bool print_person(pb_istream_t *stream)
 {
-    Person x = Person_default;
-    x.phone.funcs.decode = &print_phonenumber;
+    int i;
+    Person person;
     
-    if (!pb_decode(stream, Person_fields, &x))
+    if (!pb_decode(stream, Person_fields, &person))
         return false;
     
-    printf("Person: name '%s' id '%d' email '%s'\n", x.name, x.id, x.email);
+    printf("Person: name '%s' id '%d' email '%s'\n", person.name, person.id, person.email);
+    
+    for (i = 0; i < person.phone_size; i++)
+    {
+        Person_PhoneNumber *phone = &person.phone[i];
+        printf("PhoneNumber: number '%s' type '%d'\n", phone->number, phone->type);
+    }
+    
     return true;
 }
 
@@ -91,10 +108,10 @@ bool my_read(pb_istream_t *stream, char *buf, size_t count)
 
 int main()
 {
-    char buffer[512];
+    uint8_t buffer[512];
     size_t size = fread(buffer, 1, 512, stdin);
     
-    pb_istream_t stream = {&my_read, buffer, size};
+    pb_istream_t stream = pb_istream_from_buffer(buffer, size);
     if (!print_person(&stream))
         printf("Parsing failed.\n");