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Annotation of gforth/power.h, revision 1.5

1.3       anton       1: /* This is the machine-specific part for the Power (incl. PPC) architecture
1.1       anton       2: 
1.3       anton       3:   Copyright (C) 1995 Free Software Foundation, Inc.
                      4: 
                      5:   This file is part of Gforth.
                      6: 
                      7:   Gforth is free software; you can redistribute it and/or
                      8:   modify it under the terms of the GNU General Public License
                      9:   as published by the Free Software Foundation; either version 2
                     10:   of the License, or (at your option) any later version.
                     11: 
                     12:   This program is distributed in the hope that it will be useful,
                     13:   but WITHOUT ANY WARRANTY; without even the implied warranty of
                     14:   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
                     15:   GNU General Public License for more details.
                     16: 
                     17:   You should have received a copy of the GNU General Public License
                     18:   along with this program; if not, write to the Free Software
                     19:   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
1.1       anton      20: */
                     21: 
                     22: #if !defined(USE_TOS) && !defined(USE_NO_TOS)
                     23: #define USE_TOS
                     24: #endif
                     25: 
                     26: #ifndef INDIRECT_THREADED
                     27: #ifndef DIRECT_THREADED
                     28: /* #define DIRECT_THREADED */
                     29: #endif
                     30: #endif
                     31: 
                     32: #include "32bit.h"
                     33: 
                     34: /* cache flush stuff */
                     35: #warning If you get assembly errors, here is the reason why
1.2       anton      36: #define FLUSH_ICACHE(addr,size)   asm("icbi (%0); isync"::"b"(addr))
1.1       anton      37: /* this assumes size=4 */
                     38: /* the mnemonics are for the PPC and the syntax is a wild guess; for
                     39:    Power the mnemonic for the isync instruction is "ics" and I have
                     40:    not found an equivalent for the icbi instruction in my reference.
                     41: */
1.2       anton      42: 
                     43: #ifdef DIRECT_THREADED
                     44: #warning Direct threading for Power has not been tested
1.1       anton      45: 
                     46: /* PFA gives the parameter field address corresponding to a cfa */
                     47: #define PFA(cfa)       (((Cell *)cfa)+2)
                     48: /* PFA1 is a special version for use just after a NEXT1 */
                     49: /* the improvement here is that we may destroy cfa before using PFA1 */
                     50: #define PFA1(cfa)       PFA(cfa)
                     51: 
                     52: /* I'll assume the code resides in the lower (or upper) 32M of the
                     53:    address space and use absolute addressing in the jumps to the
                     54:    handlers. This makes it possible to use the full address space for
                     55:    direct threaded Forth (even on 64-bit PowerPCs). However, the
                     56:    linker has to ensure that this really happens */
                     57: 
                     58: #define JUMP_TARGET_BITS 0
                     59: /* assuming the code is in the lower 32M; if it is in the upper 32M,
                     60:    define JUMP_TARGET_BITS as ~0x3ffffff */
                     61: #define JUMP_MASK      0x3fffffc
                     62: 
                     63: /* CODE_ADDRESS is the address of the code jumped to through the code field */
                     64: #define CODE_ADDRESS(cfa)      ((Label)(((*(unsigned *)(cfa))&JUMP_MASK)|JUMP_TARGET_BITS))
                     65: 
                     66: /* MAKE_CF creates an appropriate code field at the cfa; ca is the
                     67:    code address. For those familiar with assembly, this is a `ba'
                     68:    instruction in both Power and PowerPC assembly languages */
                     69: #define MAKE_CF(cfa,ca)        (*(long *)(cfa) = 0x48000002|(ca))
                     70: 
                     71: /* this is the point where the does code for the word with the xt cfa
                     72:    starts. Since a branch is only a cell on Power, we can use the
                     73:    second cell of the cfa for storing the does address */
1.4       anton      74: #define DOES_CODE(cfa) \
1.5     ! anton      75:      ({ unsigned *_cfa=(unsigned *)(cfa); \
1.4       anton      76:        _cfa[0]==(0x48000002|&&docol) ? DOES_CODE1(_cfa) : 0; })
                     77:    
                     78: 
                     79:        DOES_CODE(label)
1.1       anton      80: /* this is a special version of DOES_CODE for use in dodoes */
1.4       anton      81: #define DOES_CODE1(cfa)        ((Xt *)(((long *)(cfa))[1]))
1.1       anton      82: 
                     83: /* the does handler resides between DOES> and the following Forth
                     84:    code. Since the code-field jumps directly to dodoes, the
                     85:    does-handler is not needed for the Power architecture */
                     86: #define DOES_HANDLER_SIZE       8
                     87: #define MAKE_DOES_HANDLER(addr)   0
                     88: 
                     89: /* This makes a code field for a does-defined word. doesp is the
                     90:    address of the does-code. On the PPC, the code field consists of a
                     91:    jump to dodoes and the address of the does code */
                     92: #define MAKE_DOES_CF(cfa,doesp) ({Xt *_cfa = (Xt *)(cfa); \
                     93:                                    MAKE_CF(_cfa, symbols[DODOES]); \
                     94:                                    _cfa[1] = (doesp); })
                     95: #endif