aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
-rw-r--r--docs/abi-spec.rst15
1 files changed, 10 insertions, 5 deletions
diff --git a/docs/abi-spec.rst b/docs/abi-spec.rst
index 8bd6d1a7..c93ce25b 100644
--- a/docs/abi-spec.rst
+++ b/docs/abi-spec.rst
@@ -451,13 +451,18 @@ Non-standard Packed Mode
Solidity supports a non-standard packed mode where:
- no :ref:`function selector <abi_function_selector>` is encoded,
-- short types are not zero padded and
+- types shorter than 32 bytes are neither zero padded nor sign extended and
- dynamic types are encoded in-place and without the length.
-As an example encoding ``uint1, bytes1, uint8, string`` with values ``1, 0x42, 0x2424, "Hello, world!"`` results in ::
+As an example encoding ``int1, bytes1, uint16, string`` with values ``-1, 0x42, 0x2424, "Hello, world!"`` results in ::
- 0x0142242448656c6c6f2c20776f726c6421
- ^^ uint1(1)
+ 0xff42242448656c6c6f2c20776f726c6421
+ ^^ int1(-1)
^^ bytes1(0x42)
- ^^^^ uint8(0x2424)
+ ^^^^ uint16(0x2424)
^^^^^^^^^^^^^^^^^^^^^^^^^^ string("Hello, world!") without a length field
+
+More specifically, each statically-sized type takes as many bytes as its range has
+and dynamically-sized types like ``string``, ``bytes`` or ``uint[]`` are encoded without
+their length field. This means that the encoding is ambiguous as soon as there are two
+dynamically-sized elements.