diff options
Diffstat (limited to 'encode.c')
| -rw-r--r-- | encode.c | 304 |
1 files changed, 304 insertions, 0 deletions
diff --git a/encode.c b/encode.c new file mode 100644 index 0000000..687dbfe --- /dev/null +++ b/encode.c @@ -0,0 +1,304 @@ +#include <stdlib.h> +#include <stddef.h> +#include <stdio.h> +#include <string.h> + +#include "gob.h" +#include "encode.h" + +static int sNextTypeId = 65; + +unsigned long long flip_unsigned_long_long(unsigned long long ull) { + ull = ((ull >> 8) & 0x00FF00FF00FF00FF) | ((ull & 0x00FF00FF00FF00FF) << 8 ); + ull = ((ull >> 16) & 0x0000FFFF0000FFFF) | ((ull & 0x0000FFFF0000FFFF) << 16 ); + ull = ((ull >> 32) ) | ((ull ) << 32 ); + return ull; +} + +int gob_allocate_type_id() { + return sNextTypeId++; +} + +// a return value of buf_size or more means that output +// was truncated. +int gob_encode_unsigned_long_long(char *buf, size_t buf_size, unsigned long long ull) { + if (ull < 128) { + if (buf_size >= 1) { + *buf = (char)ull; + return 1; + } + } + unsigned char *ull_ptr = (char*)&ull; + unsigned char *end_ptr = ull_ptr + (sizeof(unsigned long long)-1); + char *write_ptr = buf + 1; + int bytes_to_write = 1; + int seen_first_bit = 0; + // high byte first + while (end_ptr >= ull_ptr) { + if (*end_ptr != 0 || seen_first_bit) { + seen_first_bit = 1; + bytes_to_write++; + if (bytes_to_write <= buf_size) { + *write_ptr = *end_ptr; + write_ptr++; + } + } + end_ptr--; + } + if (buf_size >= 1) { + *buf = -1*((char)bytes_to_write-1); // byte count omits first byte + } + return bytes_to_write; +} + +int gob_encode_unsigned_int(char *buf, size_t buf_size, unsigned int i) { + return gob_encode_unsigned_long_long(buf, buf_size, (unsigned long long)i); +} + +int gob_encode_long_long(char *buf, size_t buf_size, long long i) { + unsigned long long u; + if (i < 0) { + u = (~i << 1) | 1; // complement i, bit 0 is 1 + } else { + u = (i << 1); // do not complement i, bit 0 is 0 + } + return gob_encode_unsigned_long_long(buf, buf_size, u); +} + +int gob_encode_int(char *buf, size_t buf_size, int i) { + unsigned int u; + if (i < 0) { + u = (~i << 1) | 1; // complement i, bit 0 is 1 + } else { + u = (i << 1); // do not complement i, bit 0 is 0 + } + return gob_encode_unsigned_int(buf, buf_size, u); +} + +int gob_encode_boolean(char *buf, size_t buf_size, int b) { + return gob_encode_unsigned_long_long(buf, buf_size, b != 0); +} + +int gob_encode_double(char *buf, size_t buf_size, double d) { + return gob_encode_unsigned_long_long(buf, buf_size, flip_unsigned_long_long(*(unsigned long long*)&d)); +} + +int gob_encode_string(char *buf, size_t buf_size, const char *s) { + size_t len = strlen(s); + int encoded_len_size = gob_encode_unsigned_int(buf, buf_size, len); + buf += encoded_len_size; + buf_size -= encoded_len_size; + if (buf_size > 0) { + strncpy(buf, s, buf_size); + } + return len + encoded_len_size; +} + +int gob_start_type_definition(char *buf, size_t buf_size, int id, int type) { + int total_size = 0; + int num_bytes = 0; + char *write_ptr = buf; + + num_bytes = gob_start_struct(write_ptr, buf_size); + write_ptr += num_bytes; + buf_size -= num_bytes; + total_size += num_bytes; + + num_bytes = gob_encode_int(write_ptr, buf_size, -1*id); + write_ptr += num_bytes; + buf_size -= num_bytes; + total_size += num_bytes; + + int type_delta = 0; + switch (type) { + case GOB_ARRAYTYPE_ID: + type_delta = 1; + break; + case GOB_SLICETYPE_ID: + type_delta = 2; + break; + case GOB_STRUCTTYPE_ID: + default: + type_delta = 3; + break; + case GOB_MAPTYPE_ID: + type_delta = 4; + break; + } + + num_bytes = gob_encode_unsigned_int(write_ptr, buf_size, type_delta); + write_ptr += num_bytes; + buf_size -= num_bytes; + total_size += num_bytes; + + return total_size; +} + +int gob_end_type_definition(char *buf, size_t buf_size) { + // just the end of the wireType struct + return gob_end_struct(buf, buf_size); +} + +int gob_start_struct_type(char *buf, size_t buf_size, const char *name, int id) { + int total_size = 0; + int num_bytes = 0; + char *write_ptr = buf; + + num_bytes = gob_start_struct(write_ptr, buf_size); + write_ptr += num_bytes; + buf_size -= num_bytes; + total_size += num_bytes; + + num_bytes = gob_encode_unsigned_int(write_ptr, buf_size, 1); + write_ptr += num_bytes; + buf_size -= num_bytes; + total_size += num_bytes; + + num_bytes = gob_encode_common_type(write_ptr, buf_size, name, id); + write_ptr += num_bytes; + buf_size -= num_bytes; + total_size += num_bytes; + + return total_size; +} + +int gob_end_struct_type(char *buf, size_t buf_size) { + // just the end of the wireType struct + return gob_end_struct(buf, buf_size); +} + +int gob_encode_string_int_helper(char *buf, size_t buf_size, const char *name, int id) { + int total_size = 0; + int num_bytes = 0; + char *write_ptr = buf; + + num_bytes = gob_start_struct(write_ptr, buf_size); + write_ptr += num_bytes; + buf_size -= num_bytes; + total_size += num_bytes; + + int fieldDelta = 1; + if (name == NULL || *name == '\0') { // in go, null and "" are the same + fieldDelta ++; + } else { + num_bytes = gob_encode_unsigned_int(write_ptr, buf_size, fieldDelta); + write_ptr += num_bytes; + buf_size -= num_bytes; + total_size += num_bytes; + num_bytes = gob_encode_string(write_ptr, buf_size, name); + write_ptr += num_bytes; + buf_size -= num_bytes; + total_size += num_bytes; + } + if (id != 0) { + num_bytes = gob_encode_unsigned_int(write_ptr, buf_size, fieldDelta); + write_ptr += num_bytes; + buf_size -= num_bytes; + total_size += num_bytes; + num_bytes = gob_encode_int(write_ptr, buf_size, id); + write_ptr += num_bytes; + buf_size -= num_bytes; + total_size += num_bytes; + } + + num_bytes = gob_end_struct(write_ptr, buf_size); + write_ptr += num_bytes; + buf_size -= num_bytes; + total_size += num_bytes; + + return total_size; +} + +int gob_encode_common_type(char *buf, size_t buf_size, const char *name, int id) { + return gob_encode_string_int_helper(buf, buf_size, name, id); +} + +int gob_encode_field_type(char *buf, size_t buf_size, const char *name, int id) { + return gob_encode_string_int_helper(buf, buf_size, name, id); +} + +int gob_encode_array_type(char *buf, size_t buf_size, const char *name, int id, int elem_type, int len) { + int total_size = 0; + char *write_ptr = buf; + int num_bytes = gob_start_struct(write_ptr, buf_size); + write_ptr += num_bytes; + buf_size -= num_bytes; + total_size += num_bytes; + + num_bytes = gob_encode_unsigned_int(write_ptr, buf_size, 1); + write_ptr += num_bytes; + buf_size -= num_bytes; + total_size += num_bytes; + + num_bytes = gob_encode_common_type(write_ptr, buf_size, name, id); + write_ptr += num_bytes; + buf_size -= num_bytes; + total_size += num_bytes; + + int field_delta = 1; + if (elem_type == 0) { + field_delta++; + } else { + num_bytes = gob_encode_unsigned_int(write_ptr, buf_size, field_delta); + write_ptr += num_bytes; + buf_size -= num_bytes; + total_size += num_bytes; + num_bytes = gob_encode_int(write_ptr, buf_size, elem_type); + write_ptr += num_bytes; + buf_size -= num_bytes; + total_size += num_bytes; + } + + if (len == 0) { + field_delta++; + } else { + num_bytes = gob_encode_unsigned_int(write_ptr, buf_size, field_delta); + write_ptr += num_bytes; + buf_size -= num_bytes; + total_size += num_bytes; + num_bytes = gob_encode_int(write_ptr, buf_size, len); + write_ptr += num_bytes; + buf_size -= num_bytes; + total_size += num_bytes; + } + + num_bytes = gob_end_struct(write_ptr, buf_size); + write_ptr += num_bytes; + buf_size -= num_bytes; + total_size += num_bytes; + + return total_size; +} + +int gob_encode_slice_type(char *buf, size_t buf_size, const char *name, int id, int elem_type) { + // array type will not output len if it is 0 + return gob_encode_array_type(buf, buf_size, name, id, elem_type, 0); +} + +int gob_start_array(char *buf, size_t buf_size, size_t size) { + return gob_encode_unsigned_int(buf, buf_size, size); +} + +int gob_end_array(char *buf, size_t buf_size) { + return 0; +} + +int gob_start_slice(char *buf, size_t buf_size, size_t size) { + return gob_encode_unsigned_int(buf, buf_size, size); +} + +int gob_end_slice(char *buf, size_t buf_size) { + return 0; +} + +int gob_start_struct(char *buf, size_t buf_size) { + return 0; +} + +int gob_end_struct(char *buf, size_t buf_size) { + if (buf_size >= 1) { + *buf = '\0'; + } + return 1; +} + |