# gizlang:runtime

The runtime written in Gizlang: what the compiler lowers a construct to (the compiler appends this module wherever string( occurs). string(x) of bytes checks them with utf8Valid, which bytes.isUtf8 (gizlang:text) shares.

```gizlang
import * as Runtime from "gizlang:runtime";
```

## Functions

### `blockAt`

```gizlang
function blockAt(data: bytes, i: i64, end: i64): u8x32
```

32 bytes of data from i, zeros past end (never read past it).

Effects: fail.

### `utf8Valid`

```gizlang
function utf8Valid(self: bytes, start: i64, end: i64): bool
```

Whether bytes start..end of self are valid UTF-8 (RFC 3629), 32 bytes a
step: three nibble lookups classify each byte
against the one before (J. Keiser and D. Lemire, "Validating UTF-8 In Less
Than One Instruction Per Byte", 2021); an ASCII block only carries the check
of the block before.

Effects: fail.