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author | Indrajith K L | 2022-12-03 17:00:20 +0530 |
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committer | Indrajith K L | 2022-12-03 17:00:20 +0530 |
commit | f5c4671bfbad96bf346bd7e9a21fc4317b4959df (patch) | |
tree | 2764fc62da58f2ba8da7ed341643fc359873142f /v_windows/v/vlib/encoding/base58/base58.v | |
download | cli-tools-windows-master.tar.gz cli-tools-windows-master.tar.bz2 cli-tools-windows-master.zip |
Diffstat (limited to 'v_windows/v/vlib/encoding/base58/base58.v')
-rw-r--r-- | v_windows/v/vlib/encoding/base58/base58.v | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/v_windows/v/vlib/encoding/base58/base58.v b/v_windows/v/vlib/encoding/base58/base58.v new file mode 100644 index 0000000..fb2ff72 --- /dev/null +++ b/v_windows/v/vlib/encoding/base58/base58.v @@ -0,0 +1,181 @@ +// algorthim is adapted from https://github.com/mr-tron/base58 under the MIT license + +module base58 + +import math + +// encode_int encodes any integer type to base58 string with Bitcoin alphabet +pub fn encode_int(input int) ?string { + return encode_int_walpha(input, alphabets['btc']) +} + +// encode_int_walpha any integer type to base58 string with custom alphabet +pub fn encode_int_walpha(input int, alphabet Alphabet) ?string { + if input <= 0 { + return error(@MOD + '.' + @FN + ': input must be greater than zero') + } + + mut buffer := []byte{} + + mut i := input + for i > 0 { + remainder := i % 58 + buffer << alphabet.encode[i8(remainder)] + // This needs to be casted so byte inputs can + // be used. i8 because remainder will never be + // over 58. + i = i / 58 + } + + return buffer.reverse().bytestr() +} + +// encode encodes byte array to base58 with Bitcoin alphabet +pub fn encode(input string) string { + return encode_walpha(input, alphabets['btc']) +} + +// encode_walpha encodes byte array to base58 with custom aplhabet +pub fn encode_walpha(input string, alphabet Alphabet) string { + if input.len == 0 { + return '' + } + + bin := input.bytes() + mut sz := bin.len + + mut zcount := 0 + for zcount < sz && bin[zcount] == 0 { + zcount++ + } + + // It is crucial to make this as short as possible, especially for + // the usual case of Bitcoin addresses + sz = zcount + (sz - zcount) * 555 / 406 + 1 + // integer simplification of + // ceil(log(256)/log(58)) + + mut out := []byte{len: sz} + mut i := 0 + mut high := 0 + mut carry := u32(0) + + high = sz - 1 + for b in bin { + i = sz - 1 + for carry = u32(b); i > high || carry != 0; i-- { + carry = carry + 256 * u32(out[i]) + out[i] = byte(carry % 58) + carry /= 58 + } + high = 1 + } + + // determine additional "zero-gap" in the buffer, aside from zcount + for i = zcount; i < sz && out[i] == 0; i++ {} + + // now encode the values with actual alphabet in-place + val := out[i - zcount..] + sz = val.len + for i = 0; i < sz; i++ { + out[i] = alphabet.encode[val[i]] + } + + return out[..sz].bytestr() +} + +// decode_int decodes base58 string to an integer with Bitcoin alphabet +pub fn decode_int(input string) ?int { + return decode_int_walpha(input, alphabets['btc']) +} + +// decode_int_walpha decodes base58 string to an integer with custom alphabet +pub fn decode_int_walpha(input string, alphabet Alphabet) ?int { + mut total := 0 // to hold the results + b58 := input.reverse() + for i, ch in b58 { + ch_i := alphabet.encode.bytestr().index_byte(ch) + if ch_i == -1 { + return error(@MOD + '.' + @FN + + ': input string contains values not found in the provided alphabet') + } + + val := ch_i * math.pow(58, i) + + total += int(val) + } + + return total +} + +// decode decodes base58 string using the Bitcoin alphabet +pub fn decode(str string) ?string { + return decode_walpha(str, alphabets['btc']) +} + +// decode_walpha decodes base58 string using custom alphabet +pub fn decode_walpha(str string, alphabet Alphabet) ?string { + if str.len == 0 { + return '' + } + + zero := alphabet.encode[0] + b58sz := str.len + + mut zcount := 0 + for i := 0; i < b58sz && str[i] == zero; i++ { + zcount++ + } + + mut t := u64(0) + mut c := u64(0) + + // the 32-bit algorithm stretches the result up to 2x + mut binu := []byte{len: 2 * ((b58sz * 406 / 555) + 1)} + mut outi := []u32{len: (b58sz + 3) / 4} + + for _, r in str { + if r > 127 { + panic(@MOD + '.' + @FN + + ': high-bit set on invalid digit; outside of ascii range ($r). This should never happen.') + } + if alphabet.decode[r] == -1 { + return error(@MOD + '.' + @FN + ': invalid base58 digit ($r)') + } + + c = u64(alphabet.decode[r]) + + for j := outi.len - 1; j >= 0; j-- { + t = u64(outi[j]) * 58 + c + c = t >> 32 + outi[j] = u32(t & 0xffffffff) + } + } + + // initial mask depend on b58sz, on further loops it always starts at 24 bits + mut mask := (u32(b58sz % 4) * 8) + if mask == 0 { + mask = 32 + } + mask -= 8 + + mut out_len := 0 + for j := 0; j < outi.len; j++ { + for mask < 32 { + binu[out_len] = byte(outi[j] >> mask) + mask -= 8 + out_len++ + } + mask = 24 + } + + // find the most significant byte post-decode, if any + for msb := zcount; msb < binu.len; msb++ { // loop relies on u32 overflow + if binu[msb] > 0 { + return binu[msb - zcount..out_len].bytestr() + } + } + + // it's all zeroes + return binu[..out_len].bytestr() +} |