> For the complete documentation index, see [llms.txt](https://0x29a.gitbook.io/0x29a-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://0x29a.gitbook.io/0x29a-docs/memory-and-analysis/func.md).

# func

**analysis · global: `func`**

Function-boundary detection and cross-references (xrefs), built on top of `disasm`.

### `func.start(addr) -> addr | nil`

Tries to find the start of the function containing `addr` (scans backwards until it finds a recognizable prologue).

### `func.size(addr) -> integer`

Computes the size in bytes of the function starting at `addr`.

### `func.calls(addr) -> [addr]`

Lists the target addresses of every `call` inside the function at `addr`.

### `func.xrefs_to(addr) -> [{from, to, type}]`

Who calls/jumps/references `addr`. `type` is `"call"`, `"jmp"`, or `"data"`.

### `func.xrefs_from(addr) -> [{from, to, type}]`

The reverse: where the function at `addr` calls/jumps/references.

```lua
local start = func.start(rip)
print("function starts at", string.format("0x%X", start))

for _, x in ipairs(func.xrefs_to(start)) do
    print(string.format("  referenced from 0x%X (%s)", x.from, x.type))
end
```

See the global helper [`analyze(addr)`](/0x29a-docs/globals/helpers.md#analyze-a) which combines `func.*` and `sym.*` into a ready-to-print summary.


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