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chriseth merged 3 commits into from
May 14, 2018
Merged

Add logic builtins to Julia and update type conversion prototypes #3238

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63c81bc
Add logic builtins to Julia and fix some typos
axic Nov 22, 2017
af0d73f
Remove stop() as it is the same as return(0,0) in Julia sepcs
axic Feb 27, 2018
f753dda
Describe rule for type conversion functions in Julia
axic May 9, 2018
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52 changes: 36 additions & 16 deletions docs/julia.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -306,19 +306,37 @@ Type Conversion Functions
JULIA has no support for implicit type conversion and therefore functions exists to provide explicit conversion.
When converting a larger type to a shorter type a runtime exception can occur in case of an overflow.

The following type conversion functions must be available:
- ``u32tobool(x:u32) -> y:bool``
- ``booltou32(x:bool) -> y:u32``
- ``u32tou64(x:u32) -> y:u64``
- ``u64tou32(x:u64) -> y:u32``
- etc. (TBD)
Truncating conversions are supported between the following types:
- ``bool``
- ``u32``
- ``u64``
- ``u256``
- ``s256``

For each of these a type conversion function exists having the prototype in the form of ``<input_type>to<output_type>(x:<input_type>) -> y:<output_type>``,
such as ``u32tobool(x:u32) -> y:bool``, ``u256tou32(x:u256) -> y:u32`` or ``s256tou256(x:s256) -> y:u256``.

.. note::

``u32tobool(x:u32) -> y:bool`` can be implemented as ``y := not(iszerou256(x))`` and
``booltou32(x:bool) -> y:u32`` can be implemented as ``switch x case true:bool { y := 1:u32 } case false:bool { y := 0:u32 }``

Low-level Functions
-------------------

The following functions must be available:

+---------------------------------------------------------------------------------------------------------------+
| *Logic* |
+---------------------------------------------+-----------------------------------------------------------------+
| not(x:bool) -> z:bool | logical not |
+---------------------------------------------+-----------------------------------------------------------------+
| and(x:bool, y:bool) -> z:bool | logical and |
+---------------------------------------------+-----------------------------------------------------------------+
| or(x:bool, y:bool) -> z:bool | logical or |
+---------------------------------------------+-----------------------------------------------------------------+
| xor(x:bool, y:bool) -> z:bool | xor |
+---------------------------------------------+-----------------------------------------------------------------+
| *Arithmetics* |
+---------------------------------------------+-----------------------------------------------------------------+
| addu256(x:u256, y:u256) -> z:u256 | x + y |
Expand All @@ -343,15 +361,19 @@ The following functions must be available:
+---------------------------------------------+-----------------------------------------------------------------+
| mulmodu256(x:u256, y:u256, m:u256) -> z:u256| (x * y) % m with arbitrary precision arithmetics |
+---------------------------------------------+-----------------------------------------------------------------+
| ltu256(x:u256, y:u256) -> z:bool | 1 if x < y, 0 otherwise |
| ltu256(x:u256, y:u256) -> z:bool | true if x < y, false otherwise |
+---------------------------------------------+-----------------------------------------------------------------+
| gtu256(x:u256, y:u256) -> z:bool | 1 if x > y, 0 otherwise |
| gtu256(x:u256, y:u256) -> z:bool | true if x > y, false otherwise |
+---------------------------------------------+-----------------------------------------------------------------+
| sltu256(x:s256, y:s256) -> z:bool | 1 if x < y, 0 otherwise, for signed numbers in two's complement |
| sltu256(x:s256, y:s256) -> z:bool | true if x < y, false otherwise |
| | (for signed numbers in two's complement) |
+---------------------------------------------+-----------------------------------------------------------------+
| sgtu256(x:s256, y:s256) -> z:bool | 1 if x > y, 0 otherwise, for signed numbers in two's complement |
| sgtu256(x:s256, y:s256) -> z:bool | true if x > y, false otherwise |
| | (for signed numbers in two's complement) |
+---------------------------------------------+-----------------------------------------------------------------+
| equ256(x:u256, y:u256) -> z:bool | 1 if x == y, 0 otherwise |
| equ256(x:u256, y:u256) -> z:bool | true if x == y, false otherwise |
+---------------------------------------------+-----------------------------------------------------------------+
| iszerou256(x:u256) -> z:bool | true if x == 0, false otherwise |
+---------------------------------------------+-----------------------------------------------------------------+
| notu256(x:u256) -> z:u256 | ~x, every bit of x is negated |
+---------------------------------------------+-----------------------------------------------------------------+
Expand Down Expand Up @@ -405,10 +427,6 @@ The following functions must be available:
| insize:u256, out:u256, | but also keep ``caller`` |
| outsize:u256) -> r:u256 | and ``callvalue`` |
+---------------------------------------------+-----------------------------------------------------------------+
| stop() | stop execution, identical to return(0,0) |
| | Perhaps it would make sense retiring this as it equals to |
| | return(0,0). It can be an optimisation by the EVM backend. |
+---------------------------------------------+-----------------------------------------------------------------+
| abort() | abort (equals to invalid instruction on EVM) |
+---------------------------------------------+-----------------------------------------------------------------+
| return(p:u256, s:u256) | end execution, return data mem[p..(p+s)) |
Expand Down Expand Up @@ -473,6 +491,8 @@ The following functions must be available:
+---------------------------------------------+-----------------------------------------------------------------+
| *Others* |
+---------------------------------------------+-----------------------------------------------------------------+
| discard(unused:bool) | discard value |
+---------------------------------------------+-----------------------------------------------------------------+
| discardu256(unused:u256) | discard value |
+---------------------------------------------+-----------------------------------------------------------------+
| splitu256tou64(x:u256) -> (x1:u64, x2:u64, | split u256 to four u64's |
Expand All @@ -481,7 +501,7 @@ The following functions must be available:
| combineu64tou256(x1:u64, x2:u64, x3:u64, | combine four u64's into a single u256 |
| x4:u64) -> (x:u256) | |
+---------------------------------------------+-----------------------------------------------------------------+
| sha3(p:u256, s:u256) -> v:u256 | keccak(mem[p...(p+s))) |
| keccak256(p:u256, s:u256) -> v:u256 | keccak(mem[p...(p+s))) |
+---------------------------------------------+-----------------------------------------------------------------+

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