source: trunk/gcc/libffi/src/mips/o32.S

/* -----------------------------------------------------------------------
   o32.S - Copyright (c) 1996, 1998  Cygnus Solutions
   
   MIPS Foreign Function Interface 

   Permission is hereby granted, free of charge, to any person obtaining
   a copy of this software and associated documentation files (the
   ``Software''), to deal in the Software without restriction, including
   without limitation the rights to use, copy, modify, merge, publish,
   distribute, sublicense, and/or sell copies of the Software, and to
   permit persons to whom the Software is furnished to do so, subject to
   the following conditions:

   The above copyright notice and this permission notice shall be included
   in all copies or substantial portions of the Software.

   THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND, EXPRESS
   OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
   IN NO EVENT SHALL CYGNUS SOLUTIONS BE LIABLE FOR ANY CLAIM, DAMAGES OR
   OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
   ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
   OTHER DEALINGS IN THE SOFTWARE.
   ----------------------------------------------------------------------- */

#define LIBFFI_ASM      
#include <ffi.h>

/* Only build this code if we are compiling for o32 */  

#if defined(FFI_MIPS_O32)
        
#define callback a0
#define bytes    a2
#define flags    a3
                
#define SIZEOF_FRAME    ( 4 * SIZEOF_ARG + 2 * SIZEOF_ARG )

        .text
        .align  2
        .globl  ffi_call_O32
        .ent    ffi_call_O32
ffi_call_O32:   

        # Prologue
        SUBU    $sp, SIZEOF_FRAME                       # Frame size
        REG_S   $fp, SIZEOF_FRAME - 2*SIZEOF_ARG($sp)   # Save frame pointer
        REG_S   ra, SIZEOF_FRAME - 1*SIZEOF_ARG($sp)    # Save return address
        move    $fp, $sp

        move    t9, callback    # callback function pointer
        REG_S   flags, SIZEOF_FRAME + 3*SIZEOF_ARG($fp) # flags

        # Allocate at least 4 words in the argstack
        move    v0, bytes
        bge     bytes, 4 * SIZEOF_ARG, bigger   
        LI      v0, 4 * SIZEOF_ARG
        b       sixteen

bigger: 
        ADDU    t0, v0, 2 * SIZEOF_ARG -1       # make sure it is aligned 
        and     v0, t0, -2 * SIZEOF_ARG         # to an 8 byte boundry

sixteen:
        SUBU    $sp, $sp, v0    # move the stack pointer to reflect the
                                # arg space

        ADDU    a0, $sp, 4 * SIZEOF_ARG
        ADDU    a3, $fp, SIZEOF_FRAME + 3*SIZEOF_ARG

        jal     t9
        
        REG_L   t0, SIZEOF_FRAME + 3*SIZEOF_ARG($fp)  # load the flags word
        add     t2, t0, 0                          # and copy it into t2

        and     t0, ((1<<4)-1)          # mask out the return type
        SRL     t2, 4                   # shift our arg info
                
        ADDU    $sp, $sp, 4 * SIZEOF_ARG        # adjust $sp to new args

        bnez    t0, pass_d                      # make it quick for int
        REG_L   a0, 0*SIZEOF_ARG($sp)           # just go ahead and load the
        REG_L   a1, 1*SIZEOF_ARG($sp)           # four regs.
        REG_L   a2, 2*SIZEOF_ARG($sp)
        REG_L   a3, 3*SIZEOF_ARG($sp)
        b       call_it

pass_d:
        bne     t0, FFI_ARGS_D, pass_f
        l.d     $f12, 0*SIZEOF_ARG($sp) # load $fp regs from args
        REG_L   a2,   2*SIZEOF_ARG($sp) # passing a double
        REG_L   a3,   3*SIZEOF_ARG($sp)
        b       call_it

pass_f: 
        bne     t0, FFI_ARGS_F, pass_d_d
        l.s     $f12, 0*SIZEOF_ARG($sp) # load $fp regs from args
        REG_L   a1,   1*SIZEOF_ARG($sp) # passing a float
        REG_L   a2,   2*SIZEOF_ARG($sp)
        REG_L   a3,   3*SIZEOF_ARG($sp)
        b       call_it         

pass_d_d:               
        bne     t0, FFI_ARGS_DD, pass_f_f
        l.d     $f12, 0*SIZEOF_ARG($sp) # load $fp regs from args
        l.d     $f14, 2*SIZEOF_ARG($sp) # passing two doubles
        b       call_it

pass_f_f:       
        bne     t0, FFI_ARGS_FF, pass_d_f
        l.s     $f12, 0*SIZEOF_ARG($sp) # load $fp regs from args
        l.s     $f14, 1*SIZEOF_ARG($sp) # passing two floats
        REG_L   a2,   2*SIZEOF_ARG($sp)
        REG_L   a3,   3*SIZEOF_ARG($sp)
        b       call_it

pass_d_f:               
        bne     t0, FFI_ARGS_DF, pass_f_d
        l.d     $f12, 0*SIZEOF_ARG($sp) # load $fp regs from args
        l.s     $f14, 2*SIZEOF_ARG($sp) # passing double and float
        REG_L   a3,   3*SIZEOF_ARG($sp)
        b       call_it

pass_f_d:               
 # assume that the only other combination must be float then double
 #      bne     t0, FFI_ARGS_F_D, call_it
        l.s     $f12, 0*SIZEOF_ARG($sp) # load $fp regs from args
        l.d     $f14, 2*SIZEOF_ARG($sp) # passing double and float

call_it:        
        # Load the function pointer
        REG_L   t9, SIZEOF_FRAME + 5*SIZEOF_ARG($fp)

        # If the return value pointer is NULL, assume no return value.
        REG_L   t1, SIZEOF_FRAME + 4*SIZEOF_ARG($fp)
        beqz    t1, noretval

        bne     t2, FFI_TYPE_INT, retfloat
        jal     t9
        REG_L   t0, SIZEOF_FRAME + 4*SIZEOF_ARG($fp)
        REG_S   v0, 0(t0)
        b       epilogue

retfloat:
        bne     t2, FFI_TYPE_FLOAT, retdouble
        jal     t9
        REG_L   t0, SIZEOF_FRAME + 4*SIZEOF_ARG($fp)
        s.s     $f0, 0(t0)
        b       epilogue

retdouble:      
        bne     t2, FFI_TYPE_DOUBLE, noretval
        jal     t9
        REG_L   t0, SIZEOF_FRAME + 4*SIZEOF_ARG($fp)
        s.d     $f0, 0(t0)
        b       epilogue
        
noretval:       
        jal     t9
        
        # Epilogue
epilogue:       
        move    $sp, $fp        
        REG_L   $fp, SIZEOF_FRAME - 2*SIZEOF_ARG($sp) # Restore frame pointer
        REG_L   ra, SIZEOF_FRAME - 1*SIZEOF_ARG($sp)  # Restore return address
        ADDU    $sp, SIZEOF_FRAME                     # Fix stack pointer
        j       ra

        .end    ffi_call_O32
        
#endif