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[/] [ao486/] [trunk/] [rtl/] [ao486/] [commands/] [CMD_XCHG.txt] - Rev 2

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<defines>
`define CMD_XCHG        #AUTOGEN_NEXT_CMD

`define CMDEX_XCHG_implicit         4'd0
`define CMDEX_XCHG_modregrm         4'd1
`define CMDEX_XCHG_modregrm_LAST    4'd2
</defines>

<decode>
dec_ready_one && { decoder[7:3], 3'b0 } == 8'h90
`CMD_XCHG
SET(dec_cmdex, `CMDEX_XCHG_implicit);
SET(consume_one);
</decode>

<decode>
dec_ready_modregrm_one && { decoder[7:1], 1'b0 } == 8'h86
prefix_group_1_lock && `DEC_MODREGRM_IS_MOD_11
`CMD_XCHG
SET(dec_cmdex, `CMDEX_XCHG_modregrm);
IF(decoder[0] == 1'b0); SET(dec_is_8bit); ENDIF();
SET(consume_modregrm_one);
SET(dec_is_complex);
</decode>

<microcode>
`CMDEX_XCHG_modregrm
LAST(`CMDEX_XCHG_modregrm_LAST);
</microcode>

<read>
IF(rd_cmd == `CMD_XCHG && rd_cmdex == `CMDEX_XCHG_implicit);
    
    SET(rd_src_is_eax);
    SET(rd_dst_is_implicit_reg);

    SET(rd_req_implicit_reg);
    SET(rd_req_eax);

    IF(rd_mutex_busy_implicit_reg || rd_mutex_busy_eax); SET(rd_waiting); ENDIF();
ENDIF();
</read>

<read>
IF(rd_cmd == `CMD_XCHG && rd_cmdex == `CMDEX_XCHG_modregrm);
    
    SET(rd_src_is_reg);
    
    // dst: reg, src: reg
    IF(rd_modregrm_mod == 2'b11);
        
        SET(rd_dst_is_rm);
           
        IF(rd_mutex_busy_modregrm_reg || rd_mutex_busy_modregrm_rm); SET(rd_waiting); ENDIF();
    ENDIF();

    // dst: memory, src: reg
    IF(rd_modregrm_mod != 2'b11);
            
        SET(rd_dst_is_memory);
            
        IF(rd_mutex_busy_modregrm_reg || rd_mutex_busy_memory); SET(rd_waiting);
        ELSE();
            SET(read_rmw_virtual);

            IF(~(read_for_rd_ready)); SET(rd_waiting); ENDIF();
        ENDIF();
    ENDIF();
ENDIF();
</read>

<read>
IF(rd_cmd == `CMD_XCHG && rd_cmdex == `CMDEX_XCHG_modregrm_LAST);
    
    SET(rd_dst_is_reg);
    SET(rd_req_reg);
    
    IF(rd_modregrm_mod == 2'b11);
        SET(rd_req_rm);
    ENDIF();
    
    IF(rd_modregrm_mod != 2'b11);
        SET(rd_req_memory);
    ENDIF();
ENDIF();
</read>

<execute>
IF(exe_cmd == `CMD_XCHG && exe_cmdex == `CMDEX_XCHG_implicit);
    
    SET(exe_result,  src);
    SET(exe_result2, dst);

ENDIF();
</execute>

<execute>
IF(exe_cmd == `CMD_XCHG && exe_cmdex == `CMDEX_XCHG_modregrm);
    
    SET(exe_result,  src);
    SAVE(exe_buffer, dst);
ENDIF();
</execute>

<execute>
IF(exe_cmd == `CMD_XCHG && exe_cmdex == `CMDEX_XCHG_modregrm_LAST);
    
    SET(exe_result, exe_buffer);
    
ENDIF();
</execute>

<write>
IF(wr_cmd == `CMD_XCHG && wr_cmdex == `CMDEX_XCHG_implicit);
    SET(write_regrm);
    
    SAVE(eax, (wr_operand_16bit)? { eax[31:16], result2[15:0] } : result2);
ENDIF();
</write>

<write>
IF(wr_cmd == `CMD_XCHG && wr_cmdex == `CMDEX_XCHG_modregrm);
    IF(wr_dst_is_memory && ~(write_for_wr_ready)); SET(wr_waiting); ENDIF();

    SET(write_regrm,             wr_dst_is_rm);
    SET(write_rmw_virtual,       wr_dst_is_memory);
    
    SET(wr_not_finished);
ENDIF();
</write>

<write>
IF(wr_cmd == `CMD_XCHG && wr_cmdex == `CMDEX_XCHG_modregrm_LAST);
    
    SET(write_regrm);
ENDIF();
</write>

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