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Annotation of nono/vm/gvram.cpp, revision 1.1.1.9

1.1       root        1: //
                      2: // nono
1.1.1.3   root        3: // Copyright (C) 2020 nono project
                      4: // Licensed under nono-license.txt
1.1       root        5: //
                      6: 
                      7: //
                      8: // GVRAM
                      9: //
1.1.1.6   root       10: 
1.1       root       11: // GVRAM はワード単位でホストバイトオーダ配置なので、
                     12: // バイトアクセス時は HB() マクロを使用のこと。
                     13: 
1.1.1.6   root       14: #include "gvram.h"
                     15: #include "videoctlr.h"
                     16: 
1.1.1.8   root       17: // InsideOut p.135
                     18: static const busdata wait = busdata::Wait(9 * 40_nsec);
                     19: 
1.1.1.6   root       20: // コンストラクタ
1.1       root       21: GVRAMDevice::GVRAMDevice()
1.1.1.7   root       22:        : inherited(OBJ_GVRAM)
1.1       root       23: {
1.1.1.7   root       24:        uint devlen = 0x20'0000;        // XXX とりあえず
1.1       root       25: 
1.1.1.2   root       26:        mem.reset(new uint8[devlen]);
1.1       root       27: }
                     28: 
1.1.1.6   root       29: // デストラクタ
1.1       root       30: GVRAMDevice::~GVRAMDevice()
                     31: {
                     32: }
                     33: 
1.1.1.9 ! root       34: inline uint32
        !            35: GVRAMDevice::Decoder(uint32 addr) const
1.1       root       36: {
1.1.1.9 ! root       37:        return addr - baseaddr;
1.1       root       38: }
                     39: 
1.1.1.8   root       40: busdata
1.1.1.9 ! root       41: GVRAMDevice::Read(busaddr addr)
1.1       root       42: {
1.1.1.9 ! root       43:        uint32 offset = Decoder(addr.Addr());
1.1.1.8   root       44:        busdata data;
1.1.1.9 ! root       45: 
        !            46:        data = *(uint16 *)&mem[offset & ~1U];
1.1.1.8   root       47:        data |= wait;
1.1.1.9 ! root       48:        data |= BusData::Size2;
1.1.1.8   root       49:        return data;
1.1       root       50: }
                     51: 
1.1.1.8   root       52: busdata
1.1.1.9 ! root       53: GVRAMDevice::Write(busaddr addr, uint32 data)
1.1       root       54: {
1.1.1.9 ! root       55:        uint32 offset = Decoder(addr.Addr());
        !            56:        uint32 reqsize = addr.GetSize();
        !            57:        uint32 datasize = std::min(2 - (offset & 1U), reqsize);
        !            58:        data >>= (reqsize - datasize) * 8;
        !            59: 
        !            60:        if (datasize == 1) {
        !            61:                mem[HB(offset)] = data;
        !            62:        } else {
        !            63:                *(uint16 *)&mem[offset] = data;
        !            64:        }
        !            65: 
        !            66:        busdata r = wait;
        !            67:        r |= busdata::Size(datasize);
        !            68:        return r;
1.1       root       69: }
                     70: 
1.1.1.8   root       71: busdata
1.1.1.9 ! root       72: GVRAMDevice::Peek1(uint32 addr)
1.1       root       73: {
1.1.1.9 ! root       74:        uint32 offset = Decoder(addr);
        !            75:        return mem[HB(offset)];
1.1       root       76: }

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