hex.input_dec_int_until

dst[:n] = the signed decimal number read from input (two’s complement, mod 16^n).

Reads an optional leading '-', then ASCII '0'..'9', and STOPS at the first non-digit byte, which gets stored in stop_byte[:2] (note that a leading '+' stops with dst=0). The primitive behind hex.input_dec_int.

Signature

def input_dec_int_until n, dst, stop_byte @ sign_hi, do_minus, loop, digit_lo, add_digit, finish, digit, neg, end { ... }

Defined in hex/input.fj — lines 126–156 (view on GitHub).

Complexity

  • Time: ~ nd(10@+39)    (d = number of digits)

  • Space: ~ n(10.5@+149)

See the complexity glossary for what @, w, dw, dbit, n mean.

Requires init

The following must be initialised before this macro is invoked:

  • hex.init

Source

Click to view the macro body

def input_dec_int_until n, dst, stop_byte @ sign_hi, do_minus, loop, digit_lo, add_digit, finish, digit, neg, end {
    .zero n, dst
    .zero n, digit
    bit.zero neg
    .input stop_byte
    .if_flags stop_byte+dw, 1<<2, loop, sign_hi      // high nibble 2 -> maybe '-'
  sign_hi:
    .if_flags stop_byte, 1<<0xD, loop, do_minus      // '-' (0x2D) negates; else it's the stop byte
  do_minus:
    bit.not neg
    .input stop_byte
  loop:
    .if_flags stop_byte+dw, 1<<3, finish, digit_lo   // high nibble != 3 -> not '0'-'9' -> stop
  digit_lo:
    .if_flags stop_byte, (1<<10)-1, finish, add_digit
  add_digit:
    .mul10 n, dst
    .zero digit
    .xor digit, stop_byte
    .add n, dst, digit
    .input stop_byte
    ;loop
  finish:
    bit.if0 neg, end
    .neg n, dst
    ;end

  digit: hex.vec n
  neg:   bit.bit
  end:
}

Depends on

Used by

Example uses

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