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https://github.com/mikpe/pdp10-tools.git
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62 lines
2.0 KiB
C
62 lines
2.0 KiB
C
/*
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* pdp10-extint.c
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* Copyright (C) 2013-2015 Mikael Pettersson
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*
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* This file is part of pdp10-tools.
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*
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* pdp10-tools is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* pdp10-tools is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with pdp10-tools. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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* Provide types and procedures for converting 18 and 36-bit integers
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* to and from arrays of 9-bit bytes (nonets). Use these together with
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* pdp10_fread() and pdp10_fwrite() to convert 18 and 36-bit integers
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* between host-level and file-level binary representations.
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*/
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#include "pdp10-extint.h"
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/*
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* The behaviour of the PDP10's byte pointers implies a big-endian storage model,
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* as does the layout of its 72-bit long integers.
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*/
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void pdp10_uint18_to_ext(pdp10_uint18_t val, struct pdp10_ext_uint18 *ext)
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{
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ext->nonet[0] = (val >> 9) & 0x1FF;
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ext->nonet[1] = val & 0x1FF;
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}
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pdp10_uint18_t pdp10_uint18_from_ext(const struct pdp10_ext_uint18 *ext)
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{
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return
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((pdp10_uint18_t)(ext->nonet[0] & 0x1FF) << 9)
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| (ext->nonet[1] & 0x1FF);
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}
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void pdp10_uint36_to_ext(pdp10_uint36_t val, struct pdp10_ext_uint36 *ext)
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{
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ext->nonet[0] = (val >> 27) & 0x1FF;
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ext->nonet[1] = (val >> 18) & 0x1FF;
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ext->nonet[2] = (val >> 9) & 0x1FF;
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ext->nonet[3] = val & 0x1FF;
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}
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pdp10_uint36_t pdp10_uint36_from_ext(const struct pdp10_ext_uint36 *ext)
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{
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return
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((pdp10_uint36_t)(ext->nonet[0] & 0x1FF) << 27)
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| ((pdp10_uint36_t)(ext->nonet[1] & 0x1FF) << 18)
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| ((pdp10_uint36_t)(ext->nonet[2] & 0x1FF) << 9)
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| (ext->nonet[3] & 0x1FF);
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}
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