Pack bit-fields into an integer — ffi_pack

Packs multiple values into a single integer according to specified bit widths. This is useful when working with C structures that use bit-fields, which are not directly supported by libffi.

Usage

ffi_pack_bits(values, widths, base_type = ffi_uint32())

Arguments

values: Integer vector of values to pack
widths: Integer vector of bit widths for each value
base_type: FFI type for the result (default: ffi_uint32())

Value

Packed integer value

Details

Values are packed from LSB to MSB (least significant bit to most significant bit). Each value is masked to its specified width and shifted into position.

Examples

# Pack three bit-fields: enabled (1 bit), mode (3 bits), priority (4 bits)
packed <- ffi_pack_bits(c(1L, 5L, 12L), c(1L, 3L, 4L))
# Result: 0b1100101 = 0x65 = 101

# Verify by unpacking
ffi_unpack_bits(packed, c(1L, 3L, 4L))
#> [1]  1  5 12
# [1]  1  5 12