fxos/lib/lang.cpp

//---------------------------------------------------------------------------//
//  1100101 |_ mov #0, r4         __                                         //
//     11   |_ <0xb380 %5c4>     / _|_ _____ ___                             //
//     0110 |_ 3.50 -> 3.60     |  _\ \ / _ (_-<                             //
//          |_ base# + offset   |_| /_\_\___/__/                             //
//---------------------------------------------------------------------------//

#include <fxos/lang.h>
#include <fxos/util/format.h>
#include <string>
#include <cstring>

namespace FxOS {

//---
//  CPU registers
//---

// clang-format off
char const *regnames[] = {
    "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
    "r0_bank", "r1_bank", "r2_bank", "r3_bank",
    "r4_bank", "r5_bank", "r6_bank", "r7_bank",
    "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15",
    "mach", "macl", "pr", "pc",
    "sr", "ssr", "spc", "gbr", "vbr", "dbr", "sgr"
};
// clang-format on

/* Construction from string */
CpuRegister::CpuRegister(std::string name)
{
    int regcount = (sizeof regnames / sizeof regnames[0]);
    char const *name_c = name.c_str();

    for(int i = 0; i < regcount; i++) {
        if(!strcmp(regnames[i], name_c)) {
            m_name = CpuRegisterName(i + 1);
            return;
        }
    }

    m_name = CpuRegister::UNDEFINED;
}

/* Conversion to string */
std::string CpuRegister::str() const noexcept
{
    int regcount = (sizeof regnames / sizeof regnames[0]);
    int i = m_name - 1;

    if(i < 0 || i >= regcount)
        return format("<Register%d>", i + 1);
    return regnames[i];
}

//---
//  Instruction arguments
//---

/* External constructors */

AsmArgument AsmArgument_Reg(CpuRegister base)
{
    AsmArgument arg;
    arg.kind = AsmArgument::Reg;
    arg.base = base;
    return arg;
}

AsmArgument AsmArgument_Deref(CpuRegister base)
{
    AsmArgument arg;
    arg.kind = AsmArgument::Deref;
    arg.base = base;
    return arg;
}

AsmArgument AsmArgument_PostInc(CpuRegister base)
{
    AsmArgument arg;
    arg.kind = AsmArgument::PostInc;
    arg.base = base;
    return arg;
}

AsmArgument AsmArgument_PreDec(CpuRegister base)
{
    AsmArgument arg;
    arg.kind = AsmArgument::PreDec;
    arg.base = base;
    return arg;
}

AsmArgument AsmArgument_StructDeref(int disp, int opsize, CpuRegister base)
{
    AsmArgument arg;
    arg.kind = AsmArgument::StructDeref;
    arg.base = base;
    arg.disp = disp;
    arg.opsize = opsize;
    return arg;
}

AsmArgument AsmArgument_ArrayDeref(CpuRegister index, CpuRegister base)
{
    AsmArgument arg;
    arg.kind = AsmArgument::ArrayDeref;
    arg.base = base;
    arg.index = index;
    return arg;
}

AsmArgument AsmArgument_PcRel(int disp, int opsize)
{
    AsmArgument arg;
    arg.kind = AsmArgument::PcRel;
    arg.disp = disp;
    arg.opsize = opsize;
    return arg;
}

AsmArgument AsmArgument_PcJump(int disp)
{
    AsmArgument arg;
    arg.kind = AsmArgument::PcJump;
    arg.disp = disp;
    return arg;
}

AsmArgument AsmArgument_PcAddr(int disp)
{
    AsmArgument arg;
    arg.kind = AsmArgument::PcAddr;
    arg.disp = disp;
    return arg;
}

AsmArgument AsmArgument_Imm(int imm)
{
    AsmArgument arg;
    arg.kind = AsmArgument::Imm;
    arg.imm = imm;
    return arg;
}

/* String representation */
std::string AsmArgument::str() const
{
    switch(kind) {
    case AsmArgument::Reg:
        return base.str();
    case AsmArgument::Deref:
        return format("@%s", base.str());
    case AsmArgument::PostInc:
        return format("@%s+", base.str());
    case AsmArgument::PreDec:
        return format("@-%s", base.str());
    case AsmArgument::StructDeref:
        return format("@(%d,%s)", disp, base.str().c_str());
    case AsmArgument::ArrayDeref:
        return format("@(%s,%s)", index.str().c_str(), base.str().c_str());
    case AsmArgument::PcRel:
        return format("@(%d,pc)", disp);
    case AsmArgument::PcJump:
        return format("pc+%d", disp);
    case AsmArgument::PcAddr:
        return format("pc+%u", disp);
    case AsmArgument::Imm:
        return format("#%d", imm);
    default:
        return "(invalid)";
    }
}

//---
//  Instruction management
//---

AsmInstruction::AsmInstruction(char const *mn):
    opcode {0}, opsize {0}, arg_count {0}
{
    int len = strlen(mn);
    int pos = std::max(0, len - 2);

    if(!strncmp(mn + pos, ".b", 2)) {
        opsize = 1;
        len -= 2;
    }
    else if(!strncmp(mn + pos, ".w", 2)) {
        opsize = 2;
        len -= 2;
    }
    else if(!strncmp(mn + pos, ".l", 2)) {
        opsize = 4;
        len -= 2;
    }

    len = std::min(len, 11);
    strncpy(mnemonic, mn, len);
    mnemonic[len] = 0;
}

AsmInstruction::AsmInstruction(char const *mn, AsmArgument arg):
    AsmInstruction(mn)
{
    args[0] = arg;
    arg_count = 1;
}

AsmInstruction::AsmInstruction(
    char const *mn, AsmArgument arg1, AsmArgument arg2):
    AsmInstruction(mn)
{
    args[0] = arg1;
    args[1] = arg2;
    arg_count = 2;
}

//---
//  Instruction classes
//---

bool AsmInstruction::isterminal() const noexcept
{
    if(!strcmp(mnemonic, "rte") || !strcmp(mnemonic, "rts"))
        return true;

    /* Also jmp @rn which is regarded as a terminal call */
    if(!strcmp(mnemonic, "jmp") && args[0].kind == AsmArgument::Deref)
        return true;

    /* Same for braf because we can't analyse further */
    if(!strcmp(mnemonic, "braf"))
        return true;

    return false;
}

bool AsmInstruction::isjump() const noexcept
{
    return !strcmp(mnemonic, "bra");
}

bool AsmInstruction::iscondjump() const noexcept
{
    char const *v[] = {
        "bf",
        "bf.s",
        "bf/s",
        "bt",
        "bt.s",
        "bt/s",
        NULL,
    };

    for(int i = 0; v[i]; i++) {
        if(!strcmp(mnemonic, v[i]))
            return true;
    }
    return false;
}

bool AsmInstruction::iscall() const noexcept
{
    return !strcmp(mnemonic, "jsr") || !strcmp(mnemonic, "bsr")
           || !strcmp(mnemonic, "bsrf");
}

bool AsmInstruction::isdelayed() const noexcept
{
    char const *v[] = {
        "rte",
        "rts",
        "jmp",
        "jsr",
        "bra",
        "braf",
        "bsr",
        "bsrf",
        "bf.s",
        "bf/s",
        "bt.s",
        "bt/s",
        NULL,
    };

    for(int i = 0; v[i]; i++) {
        if(!strcmp(mnemonic, v[i]))
            return true;
    }
    return false;
}

bool AsmInstruction::isvaliddelayslot() const noexcept
{
    // TODO: PC-relative move is a valid delay slot but it doesn't work
    return !isdelayed() && !isterminal() && !isjump() && !iscondjump()
           && strcmp(this->mnemonic, "mova") != 0;
}

} /* namespace FxOS */