kvisc/vm/pc/mem.c

// The OS/K Team licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

#include <pc/arch.h>

//----------------------------------------------------------------------------//

#define CHK_ALIGN(type)                                                     \
    if (addr % alignof(type) > 0) {                                         \
        _except(ctx, E_ALI,                                                 \
            "Non-aligned memory access: 0x%012lX (0x%012lX) by %lu",        \
            addr, real, alignof(type));                                     \
    }

//----------------------------------------------------------------------------//

static ulong readmem8(ctx_t *ctx, ulong real, ulong addr)
{
    if (addr % 2 == 0) return (ulong)ctx->mp[real] & 0xFF;
    else return ((ulong)ctx->mp[real] & 0xFF00) >> 8;
}

static ulong readmem16(ctx_t *ctx, ulong real, ulong addr)
{
    CHK_ALIGN(ushort);

    return (ulong)ctx->mp[real];
}

static ulong readmem32(ctx_t *ctx, ulong real, ulong addr)
{
    CHK_ALIGN(uint);

    ulong val = ctx->mp[real++];
    val = val | ((ulong)ctx->mp[real] << 16);

    return val;
}

static ulong readmem64(ctx_t *ctx, ulong real, ulong addr)
{
    CHK_ALIGN(ulong);

    ulong val = (ulong)ctx->mp[real++];
    val = val | ((ulong)ctx->mp[real++] << 16);
    val = val | ((ulong)ctx->mp[real++] << 32);
    val = val | ((ulong)ctx->mp[real] << 48);

    return val;
}

//----------------------------------------------------------------------------//

static void writemem8(ctx_t *ctx, ulong val, ulong real, ulong addr)
{
    ushort v = ctx->mp[real];

    if (!(addr % 2)) {
        ctx->mp[real] = (v & 0xFF00) | (val & 0xFF);
    }

    else {
        ctx->mp[real] = (v & 0xFF) | (((val & 0xFF) << 8));
    }
}

static void writemem16(ctx_t *ctx, ulong val, ulong real, ulong addr)
{
    CHK_ALIGN(ushort);

    ctx->mp[real] = val & 0xFFFF;
}

static void writemem32(ctx_t *ctx, ulong val, ulong real, ulong addr)
{
    CHK_ALIGN(uint);

    ctx->mp[real++] = val & 0xFFFF;
    ctx->mp[real] = (val >> 16) & 0xFFFF;
}

static void writemem64(ctx_t *ctx, ulong val, ulong real, ulong addr)
{
    CHK_ALIGN(ulong);

    ctx->mp[real++] = val;
    ctx->mp[real++] = (val >> 16) & 0xFFFF;
    ctx->mp[real++] = (val >> 32) & 0xFFFF;
    ctx->mp[real] = (val >> 48) & 0xFFFF;
}

//----------------------------------------------------------------------------//

#define CHK_RANGE()                                                         \
    if (addr < MEMOFF || real >= MEMSIZE) {                                 \
        _except(ctx, E_ACC,                                                 \
            "Invalid MEM access: 0x%012lX (0x%012lX)", addr, real);         \
    }

#define GETREAL()                                                           \
    addr += cr2;                                                            \
    ulong real = addr2real(addr)

#define SIGN_EXTEND(val, mask)                                              \
    (val & ((mask + 1) >> 1)                                                \
        ? (val | ~mask)                                                     \
        : val)

//----------------------------------------------------------------------------//

ulong readmem(ctx_t *ctx, ulong addr, uint len)
{
    GETREAL();
    CHK_RANGE();
    
    ulong val;

    switch (len) {
        case 1:
            val = readmem8(ctx, real, addr);
            val = SIGN_EXTEND(val, 0xFF);
            break;

        case 2:
            val = readmem16(ctx, real, addr);
            val = SIGN_EXTEND(val, 0xFFFF);
            break;

        case 4:
            val = readmem32(ctx, real, addr);
            val = SIGN_EXTEND(val, 0xFFFFFFFFUL);
            break;

        case 8:
            return readmem64(ctx, real, addr);

        default: log("readmem() bad length %d!\n", len); abort();
    }

    return val;
}

void writemem(ctx_t *ctx, ulong val, ulong addr, uint len)
{
    GETREAL();
    CHK_RANGE();

    switch (len) {
        case 1: writemem8(ctx, val, real, addr); break;
        case 2: writemem16(ctx, val, real, addr); break;
        case 4: writemem32(ctx, val, real, addr); break;
        case 8: writemem64(ctx, val, real, addr); break;
        default: log("writemem() bad length %d!\n", len); abort();
    }
}

//----------------------------------------------------------------------------//

//
// The following functions zero-extend rather than sign-extend
//

ulong readmemzx(ctx_t *ctx, ulong addr, uint len)
{
    GETREAL();
    CHK_RANGE();

    switch (len) {
        case 1: return readmem8(ctx, real, addr); break;
        case 2: return readmem16(ctx, real, addr); break;
        case 4: return readmem32(ctx, real, addr); break;
        case 8: return readmem64(ctx, real, addr); break;

        default: log("readmem() bad length %d!\n", len); abort();
    }
}

void writememzx(ctx_t *ctx, ulong val, ulong addr, uint len)
{
    GETREAL();
    CHK_RANGE();

    switch (len) {
        case 1: writemem8(ctx, val, real, addr); break;
        case 2: writemem16(ctx, val, real, addr); break;
        case 4: writemem32(ctx, val, real, addr); break;
        case 8: writemem64(ctx, val, real, addr); break;
        default: log("writemem() bad length %d!\n", len); abort();
    }
}