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binval format

binval (binary value) is yet another BSON-like format to encode JavaScript values into binary.

It's more space-efficient than BSON. It saves the space by encoding the length into the "type" byte in many cases.

See binval.ts for the implementation.

Value

(1 byte) value type
(?) optinal value body depends on type
type JS value
0 null
1 undefined
2 false
3 true
4 (body) uint8
5 (body) uint16
6 (body) uint32
7 (body) -uint8
8 (body) -uint16
9 (body) -uint32
10 (body) float64
11 (body) length-prefixed string
12 (body) length-prefixed binary data
13 (body) object with length-prefixed prop count
14 (body) array with length-prefixed item count
15 ~ 35 (no used yet)
36 ~ 44 (body) array with item count 0 ~ 8
45 ~ 53 (body) object with key count 0 ~ 8
54 ~ 86 (body) binary data with length 0 ~ 32
87 ~ 119 (body) string with length 0 ~ 32
120 ~ 127 number -7 ~ -0
128 ~ 255 number +0 ~ 127

The length-prefixed

(1 byte) uint8 small_value
if (small_value == 254)
    (2 byte) uint16 true_value
else if (small_value == 255)
    (4 byte) uint32 true_value

Object

if (use length-prefixed)
    (n byte) length-prefixed prop_count
for each prop
    (n byte) length-prefixed property key string
    (n byte) the property value

Array

if (use length-prefixed)
    (n byte) length-prefixed item_count
for each item
    (n byte) the item value