Does Python Bytearray Use Signed Integers In The C Representation?

I have written a small Cython tool for in-place sorting of structures exposing the buffer protocol in Python. It's a work in progress; please forgive any mistakes. This is just for

Solution 1:

Does Python bytearray use signed integers in the C representation?

It uses chars. Whether those are signed depends on the compiler. You can see this in Include/bytearrayobject.h. Here's the 2.7 version:

/* Object layout */
typedef struct {
    PyObject_VAR_HEAD
    /* XXX(nnorwitz): should ob_exports be Py_ssize_t? */
    int ob_exports; /* how many buffer exports */
    Py_ssize_t ob_alloc; /* How many bytes allocated */
    char *ob_bytes;
} PyByteArrayObject;

and here's the 3.5 version:

typedef struct {
    PyObject_VAR_HEAD
    Py_ssize_t ob_alloc; /* How many bytes allocated in ob_bytes */
    char *ob_bytes;      /* Physical backing buffer */
    char *ob_start;      /* Logical start inside ob_bytes */
    /* XXX(nnorwitz): should ob_exports be Py_ssize_t? */
    int ob_exports;      /* How many buffer exports */
} PyByteArrayObject;

If true, what should be considered the "right" result of the in-place sort?

A Python bytearray represents a sequence of integers in the range 0 <= elem < 256, regardless of whether the compiler considers chars to be signed. You should probably sort it as a sequence of integers in the range 0 <= elem < 256, rather than as a sequence of signed chars.

To match output of sorted, will it be sufficient on the C side to cast values to unsigned long when dealing with bytearray?

I don't know enough about Cython to say what the correct code change would be.