69 lines
2.3 KiB
C
69 lines
2.3 KiB
C
/*
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libpsxav: MDEC video + SPU/XA-ADPCM audio library
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Copyright (c) 2019, 2020 Adrian "asie" Siekierka
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Copyright (c) 2019 Ben "GreaseMonkey" Russell
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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*/
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#include <string.h>
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#include "libpsxav.h"
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static uint32_t psx_cdrom_calculate_edc(uint8_t *sector, uint32_t offset, uint32_t size)
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{
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uint32_t edc = 0;
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for (int i = offset; i < offset+size; i++) {
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edc ^= 0xFF&(uint32_t)sector[i];
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for (int ibit = 0; ibit < 8; ibit++) {
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edc = (edc>>1)^(0xD8018001*(edc&0x1));
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}
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}
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return edc;
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}
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void psx_cdrom_calculate_checksums(uint8_t *sector, psx_cdrom_sector_type_t type)
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{
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switch (type) {
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case PSX_CDROM_SECTOR_TYPE_MODE1: {
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uint32_t edc = psx_cdrom_calculate_edc(sector, 0x0, 0x810);
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sector[0x810] = (uint8_t)(edc);
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sector[0x811] = (uint8_t)(edc >> 8);
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sector[0x812] = (uint8_t)(edc >> 16);
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sector[0x813] = (uint8_t)(edc >> 24);
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memset(sector + 0x814, 0, 8);
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// TODO: ECC
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} break;
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case PSX_CDROM_SECTOR_TYPE_MODE2_FORM1: {
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uint32_t edc = psx_cdrom_calculate_edc(sector, 0x10, 0x808);
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sector[0x818] = (uint8_t)(edc);
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sector[0x819] = (uint8_t)(edc >> 8);
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sector[0x81A] = (uint8_t)(edc >> 16);
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sector[0x81B] = (uint8_t)(edc >> 24);
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// TODO: ECC
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} break;
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case PSX_CDROM_SECTOR_TYPE_MODE2_FORM2: {
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uint32_t edc = psx_cdrom_calculate_edc(sector, 0x10, 0x91C);
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sector[0x92C] = (uint8_t)(edc);
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sector[0x92D] = (uint8_t)(edc >> 8);
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sector[0x92E] = (uint8_t)(edc >> 16);
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sector[0x92F] = (uint8_t)(edc >> 24);
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} break;
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}
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} |