bits Functions

The bits module acts on blobs.

use bits

A blob can be in one of two states, either antestone or stone. In the mutable antestone state, the write functions may be used to append bits to the blob. In the immutable stone state, bits can be harvested from the blob. Bits can be written to blobs as fixed size bit fields, that is a sequence of bits with a specified length, or as a Kim.

Kim is an encoding of fit numbers. Kim is a very simple encoding that delivers 7 bits per byte. The bottom 7 bits of each byte contain data, which can be accumulated to produce fit numbers. The top bit of each byte is 1 if the byte is not the last and least byte of a number. The top bit of each byte is 0 if the byte is the last byte of a number. The last byte contains the 7 least significant bits. A first byte of 0x80 indicates negation.

bits.kim_length(value)

The kim_length function gives the length in bits of the Kim encoding of a value. If the value is a fit number, it gives a result as shown in the table. If value is a logical, it gives 1. If value is a text, it gives the length in bits of the Kim encoding of a text, giving the sum of the kim encodings of the length and each character. Otherwise, it gives null.

Write functions

The write functions append bits to the end of an antestone blob.

bits.write_bit(blob, logical)

Append a bit to the end of the blob. The logical value can be true, false, 1, or 0. Any other value will disrupt.

bits.write_blob(first_blob, second_blob)

Append second_blob to the end of first_blob.

bits.write_dec64(blob, number)

Append a 64 bit DEC64 encoded number to a stone blob.

bits.write_fit(blob, fit, length)

Append a bit field to the blob. If fit requires more bits than allowed by length, it disrupts.

bits.write_kim(blob, fit)

Append a fit number or a single character as a kim value.

bits.write_pad(blob, block_size)

Append a 1 bit to the antestone blob followed by enough 0 bits to round up the blob's length to a multiple of the block_size.

bits.write_text(blob, text)

Append a text. This will be encoded as a kim encoded length followed by a sequence of kim encoded UTF-32 characters.

Read functions

The read functions retrieve bits from a stone blob. The from arguments specifies the bit location at which to read. The beginning of the blob is 0.

bits.read_dec64(blob, from)

Retrieve a 64 bit DEC64 encoded number from a stone blob.

bits.read_kim(blob, from)

Retrieve a Kim encoded fit number from a stone blob.

bits.read_fit(blob, from, length)

Retrieve a fit number from a bit field from a stone blob.

bits.read_logical(blob, from)

Retrieve a bit from the blob. If blob is not a stone blob, or if from is out of range, it returns null.

bits.pad?(blob, from, block_size)

Return true if the stone blob's length is a multiple of the block_size (in bits), and if the difference between length and from is less than or equal to the block_size, and if the bit at from is one, and that any remaining bits are zero.

bits.read_text(blob, from)

Retrieve a Kim encoded text from a stone blob.