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AP_Math: add bitwise fetch/load 16, 24, 32bit operations

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Tom Pittenger 2020-08-21 09:18:44 -07:00 committed by Tom Pittenger
parent 935cb39dff
commit 6efaa29577
2 changed files with 90 additions and 0 deletions
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59
libraries/AP_Math/bitwise.cpp Normal file
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/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
collection of bitwise and array-wise operations.
*/
#include "bitwise.h"
void loadUint(uint8_t *b, uint16_t v, uint8_t bitCount, bool MSBfirst)
{
const uint8_t last = bitCount/8;
// count = 32
// last = 4
// MSBfirst = 1;
for (uint8_t i=0; i<last; i++) {
const uint8_t idx = MSBfirst ? last-1-i : i;
// idx = 4-1-0
b[i] = v >> (8*idx);
}
}
uint16_t fetchU16(const uint8_t *v, bool MSBfirst)
{
if (MSBfirst) {
return v[1] | (v[0]<<8);
}
return v[0] | (v[1]<<8);
}
uint32_t fetchU24(const uint8_t *v, bool MSBfirst)
{
if (MSBfirst) {
return v[2] | (v[1]<<8) | (v[0]<<16);
}
return v[0] | (v[1]<<8) | (v[2]<<16);
}
uint32_t fetchU32(const uint8_t *v, bool MSBfirst)
{
if (MSBfirst) {
return v[3] | (v[2]<<8) | (v[1]<<16) | (v[0]<<24);
}
return v[0] | (v[1]<<8) | (v[2]<<16) | (v[3]<<24);
}

31
libraries/AP_Math/bitwise.h Normal file
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/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
interfaces to ArduPilot collection of bitwise and arraywise operations
*/
#pragma once
#include <stdint.h>
void loadUint(uint8_t *b, uint16_t v, uint8_t bitCount, bool MSBfirst = true);
//void loadU16(uint8_t *b, uint16_t v, bool MSBfirst = true) { loadUx(b, v, 16, MSBfirst); }
//void loadU24(uint8_t *b, uint32_t v, bool MSBfirst = true) { loadUx(b, v, 24, MSBfirst); }
//void loadU32(uint8_t *b, uint32_t v, bool MSBfirst = true) { loadUx(b, v, 32, MSBfirst); }
uint16_t fetchU16(const uint8_t *v, bool MSBfirst = true);
uint32_t fetchU24(const uint8_t *v, bool MSBfirst = true);
uint32_t fetchU32(const uint8_t *v, bool MSBfirst = true);