core.util¶

Portable data manipulation utilities with no architecture-specific dependencies.

Overview¶

core.util provides low-level helpers that operate on raw integers and memory without relying on any x86 assembly. It covers byte and nibble extraction, endian byte-order swapping, flat memory operations (memset/memcpy), BCD-to-integer conversion, hex character parsing, and a branchless absolute value. These primitives are used throughout the kernel wherever portable, assembly-free data manipulation is required.

Dependencies¶

None.

Functions and Procedures¶

hi¶

function hi(b : uint8) : uint8;

Returns the high nibble (bits 7–4) of a byte, shifted into the low four bits of the result. Exported with the alias util_hi.

lo¶

function lo(b : uint8) : uint8;

Returns the low nibble (bits 3–0) of a byte. Exported with the alias util_lo.

switchendian¶

function switchendian(b : uint8) : uint8;

Swaps the two nibbles of a byte (equivalent to a 4-bit rotate). Exported with the alias util_switchendian.

switchendian16¶

function switchendian16(b : uint16) : uint16;

Reverses the byte order of a 16-bit value, converting between big-endian and little-endian representations.

switchendian32¶

function switchendian32(b : uint32) : uint32;

Reverses the byte order of a 32-bit value for endian conversion.

getWord¶

function getWord(i : uint32; hi : boolean) : uint16;

Extracts the high or low 16-bit word from a 32-bit value. Returns bits 31–16 when hi is true; bits 15–0 otherwise.

getByte¶

function getByte(i : uint32; index : uint8) : uint8;

Extracts a single byte from a 32-bit value by zero-based byte index (0 = least significant byte).

memset¶

procedure memset(location : uint32; value : uint8; size : uint32);

Fills size bytes starting at address location with the byte value. Does nothing if size is zero.

memcpy¶

procedure memcpy(source : uint32; dest : uint32; size : uint32);

Copies size bytes from address source to address dest byte by byte. Behaviour is undefined if the regions overlap.

BCDToUint8¶

function BCDToUint8(bcd : uint8) : uint8;

Converts a Binary-Coded Decimal byte to its unsigned integer equivalent. The high nibble is the tens digit; the low nibble is the units digit.

HexCharToDecimal¶

function HexCharToDecimal(hex : char) : uint8;

Converts a single hexadecimal character (0–9, a–f, A–F) to its decimal value 0–15. Returns 0 for unrecognised characters.

abs¶

function abs(x : sint32) : uint32;

Returns the absolute value of a signed 32-bit integer using a branchless arithmetic technique based on sign-extension, XOR, and subtraction. The result type is uint32.

Notes¶

memcpy is a simple byte loop and does not handle overlapping source and destination regions correctly. Callers must ensure regions do not overlap, or copy in the appropriate direction manually.

The hi, lo, and switchendian functions carry stable C-compatible export aliases (util_hi, util_lo, util_switchendian) for use from assembly or interop stubs.