From: Tilman Sauerbeck Date: Wed, 8 Jan 2020 11:05:50 +0000 (+0100) Subject: common: Add the varint module. X-Git-Url: http://git.code-monkey.de/?a=commitdiff_plain;h=73ec717bd09ad251dcd65ff3c5083d65cec77da3;p=gps-watch.git common: Add the varint module. --- diff --git a/SConscript.libcommon b/SConscript.libcommon index 3687908..b0864a4 100644 --- a/SConscript.libcommon +++ b/SConscript.libcommon @@ -26,6 +26,7 @@ source_files_rs = [ 'src/common/mx25l.rs', 'src/common/shell.rs', 'src/common/yencode.rs', + 'src/common/varint.rs', ] source_files_c = [ diff --git a/src/common/lib.rs b/src/common/lib.rs index 384543e..a9c4f90 100644 --- a/src/common/lib.rs +++ b/src/common/lib.rs @@ -48,3 +48,4 @@ pub mod storage; pub mod mx25l; pub mod shell; pub mod yencode; +pub mod varint; diff --git a/src/common/varint.rs b/src/common/varint.rs new file mode 100644 index 0000000..211f558 --- /dev/null +++ b/src/common/varint.rs @@ -0,0 +1,49 @@ +/* + * Copyright (c) 2017 Tilman Sauerbeck (tilman at code-monkey de) + * + * Permission is hereby granted, free of charge, to any person obtaining + * a copy of this software and associated documentation files (the + * "Software"), to deal in the Software without restriction, including + * without limitation the rights to use, copy, modify, merge, publish, + * distribute, sublicense, and/or sell copies of the Software, and to + * permit persons to whom the Software is furnished to do so, subject to + * the following conditions: + * + * The above copyright notice and this permission notice shall be + * included in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE + * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION + * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION + * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. + */ + +pub fn write_u32(buffer: &mut [u8], _n: u32) -> usize { + let shift = 7; + let mask = 1 << shift; + let mut offset = 0; + let mut n = _n; + + while n >= mask { + let b = (n | mask) as u8; + + buffer[offset] = b; + offset += 1; + + n >>= shift; + } + + buffer[offset] = n as u8; + offset += 1; + + offset +} + +pub fn write_s32(buffer: &mut [u8], n: i32) -> usize { + let u = (n << 1) ^ (n >> 31); + + write_u32(buffer, u as u32) +}