Module: B3e

Defined in:
lib/b3e.rb,
lib/b3e/version.rb

Defined Under Namespace

Classes: Invalid

Constant Summary collapse

VERSION = 
"0.1.0"

Class Method Summary collapse

Class Method Details

.c_decode(rString) ⇒ Object 



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# File 'ext/b3e/b3e_ext.c', line 87

static VALUE rb_b3e_decode(VALUE self, VALUE rString) {
  char* string = StringValuePtr(rString);

  u_int64_t length = RSTRING_LEN(rString);
  u_int64_t size = length * 6 / 8;
  u_int64_t index;

  char decoded[size];
  u_int64_t cursor = size;
  unsigned char character;
  int x;
  int byte = 0;
  int position = 0;
  int cb;

  for (index = 0; index < length; index++) {
    character = string[index];
    x = INDEX[character];

    if (x == -1) {
      rb_raise(cInvalid, "encountered a character that is not in the base62 alphabet");
    }

    if (index == length - 1) {
      byte |= x << position;
      cb = position % 8;
      position += (cb == 0 ? 0 : 8 - cb);
    } else if ((x & COMPACT_MASK) == COMPACT_MASK) {
      byte |= x << position;
      position += 5;
    } else {
      byte |= x << position;
      position += 6;
    }

    if (position >= 8) {
      cursor--;
      decoded[cursor] = byte;
      position %= 8;
      byte >>= 8;
    }
  }

  if (position > 0) {
    cursor--;
    decoded[cursor] = byte;
  }

  if (cursor > 0) {
    char resized[size];

    for (index = 0; index < size; index++) {
      resized[index] = decoded[cursor + index];
    }

    return rb_str_new(resized, size - cursor);
  } else {
    return rb_str_new(decoded, size);
  }
}

.c_encode(rString) ⇒ Object 



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# File 'ext/b3e/b3e_ext.c', line 28

static VALUE rb_b3e_encode(VALUE self, VALUE rString) {
  char* string = StringValuePtr(rString);
  char encoded[RSTRING_LEN(rString) * 8 / 5 + 1];

  int64_t cursor1 = RSTRING_LEN(rString) * 8;
  int64_t cursor2;
  int64_t i;

  char j;
  char blen1;
  char blen2;
  char shift;
  unsigned char byte;
  int written = 0;

  while (1) {
    j = 0;
    i = 0;

    cursor2 = cursor1 - 6;
    if (cursor2 <= 0) {
      cursor2 = 0;
      blen1 = cursor1;
    } else {
      i = cursor2 / 8;
      j = cursor2 % 8;
      blen1 = (i + 1) * 8 - cursor2;
      if (blen1 > 6) {
        blen1 = 6;
      }
    }

    shift = 8 - j - blen1;
    byte = (unsigned char)string[i] >> shift & ((1 << blen1) - 1);
    if (blen1 < 6 && cursor2 > 0) {
      blen2 = 6 - blen1;
      byte = (byte << blen2) | ((unsigned char)string[i + 1] >> (8 - blen2));
    }

    if ((byte & COMPACT_MASK) == COMPACT_MASK) {
      if (cursor2 > 0 || byte > MASK_5BITS) {
        cursor2++;
      }

      byte &= MASK_5BITS;
    }

    cursor1 = cursor2;
    encoded[written] = ALPHABET[byte];
    written++;

    if (cursor2 <= 0) {
      break;
    }
  }

  return rb_str_new(encoded, written);
}

.decode(value) ⇒ Object

public

Decode a Base62 string back to its original value.



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# File 'lib/b3e.rb', line 21

def self.decode(value)
  if value.size > 0
    c_decode(value)
  else
    ""
  end
end

.encode(value) ⇒ Object

public

Encode a string as Base62.



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# File 'lib/b3e.rb', line 11

def self.encode(value)
  if value.size > 0
    c_encode(value)
  else
    ""
  end
end

.version ⇒ Object 



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# File 'lib/b3e/version.rb', line 6

def self.version
  VERSION
end