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        .file   "reg_u_add.S"

/*---------------------------------------------------------------------------+

 |  reg_u_add.S                                                              |

 |                                                                           |

 | Add two valid (TW_Valid) FPU_REG numbers, of the same sign, and put the   |

 |   result in a destination FPU_REG.                                        |

 |                                                                           |

 | Copyright (C) 1992,1993,1995                                              |

 |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |

 |                       Australia.  E-mail billm@jacobi.maths.monash.edu.au |

 |                                                                           |

 | Call from C as:                                                           |

 |   void reg_u_add(FPU_REG *arg1, FPU_REG *arg2, FPU_REG *answ,             |

 |                                                int control_w)             |

 |                                                                           |

 +---------------------------------------------------------------------------*/

/*

 |    Kernel addition routine reg_u_add(reg *arg1, reg *arg2, reg *answ).

 |    Takes two valid reg f.p. numbers (TW_Valid), which are

 |    treated as unsigned numbers,

 |    and returns their sum as a TW_Valid or TW_S f.p. number.

 |    The returned number is normalized.

 |    Basic checks are performed if PARANOID is defined.

 */

#include "exception.h"

#include "fpu_emu.h"

#include "control_w.h"

.text

ENTRY(reg_u_add)

        pushl   %ebp

        movl    %esp,%ebp

        pushl   %esi

        pushl   %edi

        pushl   %ebx

        movl    PARAM1,%esi             /* source 1 */

        movl    PARAM2,%edi             /* source 2 */

#ifdef DENORM_OPERAND

        cmpl    EXP_UNDER,EXP(%esi)

        jg      xOp1_not_denorm

        call    SYMBOL_NAME(denormal_operand)

        orl     %eax,%eax

        jnz     fpu_Arith_exit

xOp1_not_denorm:

        cmpl    EXP_UNDER,EXP(%edi)

        jg      xOp2_not_denorm

        call    SYMBOL_NAME(denormal_operand)

        orl     %eax,%eax

        jnz     fpu_Arith_exit

xOp2_not_denorm:

#endif DENORM_OPERAND

        movl    EXP(%esi),%ecx

        subl    EXP(%edi),%ecx          /* exp1 - exp2 */

        jge     L_arg1_larger

        /* num1 is smaller */

        movl    SIGL(%esi),%ebx

        movl    SIGH(%esi),%eax

        movl    %edi,%esi

        negw    %cx

        jmp     L_accum_loaded

L_arg1_larger:

        /* num1 has larger or equal exponent */

        movl    SIGL(%edi),%ebx

        movl    SIGH(%edi),%eax

L_accum_loaded:

        movl    PARAM3,%edi             /* destination */

/*      movb    SIGN(%esi),%dl

        movb    %dl,SIGN(%edi) */       /* Copy the sign from the first arg */

        movl    EXP(%esi),%edx

        movl    %edx,EXP(%edi)          /* Copy exponent to destination */

        xorl    %edx,%edx               /* clear the extension */

#ifdef PARANOID

        testl   $0x80000000,%eax

        je      L_bugged

        testl   $0x80000000,SIGH(%esi)

        je      L_bugged

#endif PARANOID

/* The number to be shifted is in %eax:%ebx:%edx */

        cmpw    $32,%cx         /* shrd only works for 0..31 bits */

        jnc     L_more_than_31

/* less than 32 bits */

        shrd    %cl,%ebx,%edx

        shrd    %cl,%eax,%ebx

        shr     %cl,%eax

        jmp     L_shift_done

L_more_than_31:

        cmpw    $64,%cx

        jnc     L_more_than_63

        subb    $32,%cl

        jz      L_exactly_32

        shrd    %cl,%eax,%edx

        shr     %cl,%eax

        orl     %ebx,%ebx

        jz      L_more_31_no_low        /* none of the lowest bits is set */

        orl     $1,%edx                 /* record the fact in the extension */

L_more_31_no_low:

        movl    %eax,%ebx

        xorl    %eax,%eax

        jmp     L_shift_done

L_exactly_32:

        movl    %ebx,%edx

        movl    %eax,%ebx

        xorl    %eax,%eax

        jmp     L_shift_done

L_more_than_63:

        cmpw    $65,%cx

        jnc     L_more_than_64

        movl    %eax,%edx

        orl     %ebx,%ebx

        jz      L_more_63_no_low

        orl     $1,%edx

        jmp     L_more_63_no_low

L_more_than_64:

        movl    $1,%edx         /* The shifted nr always at least one '1' */

L_more_63_no_low:

        xorl    %ebx,%ebx

        xorl    %eax,%eax

L_shift_done:

        /* Now do the addition */

        addl    SIGL(%esi),%ebx

        adcl    SIGH(%esi),%eax

        jnc     L_round_the_result

        /* Overflow, adjust the result */

        rcrl    $1,%eax

        rcrl    $1,%ebx

        rcrl    $1,%edx

        jnc     L_no_bit_lost

        orl     $1,%edx

L_no_bit_lost:

        incl    EXP(%edi)

L_round_the_result:

        jmp     fpu_reg_round   /* Round the result */

#ifdef PARANOID

/* If we ever get here then we have problems! */

L_bugged:

        pushl   EX_INTERNAL|0x201

        call    EXCEPTION

        pop     %ebx

        jmp     L_exit

#endif PARANOID

L_exit:

        popl    %ebx

        popl    %edi

        popl    %esi

        leave

        ret