From 31550c058654edd953d9ea6f0d1ce83026e68b61 Mon Sep 17 00:00:00 2001 From: Austen Adler Date: Wed, 15 Feb 2023 20:00:12 -0500 Subject: [PATCH] Update algorithm doc --- docs/ALGORITHM.adoc | 87 +++++++++++++-------------------------------- 1 file changed, 24 insertions(+), 63 deletions(-) diff --git a/docs/ALGORITHM.adoc b/docs/ALGORITHM.adoc index 5ae4c79..035d2e3 100644 --- a/docs/ALGORITHM.adoc +++ b/docs/ALGORITHM.adoc @@ -12,71 +12,25 @@ == Data format -[source] +[source,title='this_algorithm and S2 CellID Format'] ---- -Example: Face 2, level 23 - -# Most significant 3 bits are for the face -face_number = 0b010 - -# This algorithm is always level 23 -data_bits = level * 2 = 23 * 2 = 46 - -# The bit after the data bits is always 1 -# All subsequent bits are always 0 - -Bit : 64 48 32 16 1 - : | | | | | - : 01001011101010001011100010010011 1001001100100l001100000000000000 -Face number : ^^^ -Data bits : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^ -Bit after data bits (1) : ^ -All remaining bits (0) : ^^^^^^^^^^^^^^ +=== this_algorithm Format === +WORD3 (13 bits) : vvvvvvvvvvvvv +WORD2 (13 bits) : | |vvv vvvvvvvvvv +WORD1 (13 bits) : | | |vvvvvv vvvvvvv +0000 (10 bits) : | | | |vvvvvvvvv v +Not represented : | | | | | + : | | | | | +Bit : 64 52 48 39 32 26 16 1 + : | | | | | | | | + : 0100101110101000 1011100010010011 1001001100100l00 1100000000000000 +=== S2 CellID Format === | | || | +Face number : ^^^ || | +Data bits : ^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^ ^| | +Bit after data bits (1) : ^ | +All remaining bits (0) : ^^^^^^^^^^^^^^ ---- -[source] ----- -All remaining bits (0) : vvvvvvvvvvvvvv -Bit after data bits (1) : v -Data bits : vvvvvvvvvvvvvvvvvvvvvvvvvvvvv vvvvvvvvvvvvvvvvv -Face number : vvv -Bit : 64 48 32 16 1 - : | | | | | - : 01001011101010001011100010010011 1001001100100l001100000000000000 -Not represented : ^^^^^^^^^^^^^^^ -0000 (10 bits) : ^^^^^^^^^^ -WORD1 (13 bits) : ^^^^^^ ^^^^^^^ -WORD2 (13 bits) : ^^^^^^^^^^^^^ -WORD3 (13 bits) : ^^^^^^^^^^^^^ ----- - -Alternative format (generated using link:https://github.com/luismartingarcia/protocol[protocol^]) - -[source] ----- -./protocol 'Face:3,Data:46,1:1,0:14?bits=32' - 0 1 2 3 - 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -| Face| Data | -+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -| |1| 0 | -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ----- - -[source] ----- -./protocol 'WORD3:13,WORD2:13,WORD1:13,Number:10?bits=32' - 0 1 2 3 - 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -| WORD3 | WORD2 | | -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -| WORD1 | Number | -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ----- - - == Encoding [%header,cols="2m,5a"] @@ -199,7 +153,14 @@ func cellIDFromFaceIJ(f, i, j int) CellID { ---- [source,rust] ---- -fn fij_to_cellid(f: u8, s: u32, t: u32) -> u64 { +const FACE_BITS: u64 = 3; +const NUM_FACES: u8 = 6; +const MAX_LEVEL: u64 = 30; +const POS_BITS: u64 = (2 * MAX_LEVEL) + 1; +const MAX_SIZE: u64 = 1 << MAX_LEVEL; +const WRAP_OFFSET: u64 = (NUM_FACES as u64) << POS_BITS; + +fn fij_to_cellid(f: u8, i: u32, j: u32) -> u64 { let mut n = u64::from(f) << (POS_BITS - 1); let mut bits = u32::from(f & SWAP_MASK);