Annotation of gforth/power.h, revision 1.1

1.1     ! anton       1: /*
        !             2:   Copyright 1992 by the ANSI figForth Development Group
        !             3: 
        !             4:   This is the machine-specific part for the Power (incl. PPC) architecture
        !             5: */
        !             6: 
        !             7: #if !defined(USE_TOS) && !defined(USE_NO_TOS)
        !             8: #define USE_TOS
        !             9: #endif
        !            10: 
        !            11: #ifndef INDIRECT_THREADED
        !            12: #ifndef DIRECT_THREADED
        !            13: /* #define DIRECT_THREADED */
        !            14: #endif
        !            15: #endif
        !            16: 
        !            17: #include "32bit.h"
        !            18: 
        !            19: /* cache flush stuff */
        !            20: #ifdef DIRECT_THREADED
        !            21: #warning Direct threading for Power has not been tested
        !            22: 
        !            23: #warning If you get assembly errors, here is the reason why
        !            24: #define CACHE_FLUSH(addr,size)   asm("icbi (%0); isync"::"b"(addr))
        !            25: /* this assumes size=4 */
        !            26: /* the mnemonics are for the PPC and the syntax is a wild guess; for
        !            27:    Power the mnemonic for the isync instruction is "ics" and I have
        !            28:    not found an equivalent for the icbi instruction in my reference.
        !            29: */
        !            30: 
        !            31: /* PFA gives the parameter field address corresponding to a cfa */
        !            32: #define PFA(cfa)       (((Cell *)cfa)+2)
        !            33: /* PFA1 is a special version for use just after a NEXT1 */
        !            34: /* the improvement here is that we may destroy cfa before using PFA1 */
        !            35: #define PFA1(cfa)       PFA(cfa)
        !            36: 
        !            37: /* I'll assume the code resides in the lower (or upper) 32M of the
        !            38:    address space and use absolute addressing in the jumps to the
        !            39:    handlers. This makes it possible to use the full address space for
        !            40:    direct threaded Forth (even on 64-bit PowerPCs). However, the
        !            41:    linker has to ensure that this really happens */
        !            42: 
        !            43: #define JUMP_TARGET_BITS 0
        !            44: /* assuming the code is in the lower 32M; if it is in the upper 32M,
        !            45:    define JUMP_TARGET_BITS as ~0x3ffffff */
        !            46: #define JUMP_MASK      0x3fffffc
        !            47: 
        !            48: /* CODE_ADDRESS is the address of the code jumped to through the code field */
        !            49: #define CODE_ADDRESS(cfa)      ((Label)(((*(unsigned *)(cfa))&JUMP_MASK)|JUMP_TARGET_BITS))
        !            50: 
        !            51: /* MAKE_CF creates an appropriate code field at the cfa; ca is the
        !            52:    code address. For those familiar with assembly, this is a `ba'
        !            53:    instruction in both Power and PowerPC assembly languages */
        !            54: #define MAKE_CF(cfa,ca)        (*(long *)(cfa) = 0x48000002|(ca))
        !            55: 
        !            56: /* this is the point where the does code for the word with the xt cfa
        !            57:    starts. Since a branch is only a cell on Power, we can use the
        !            58:    second cell of the cfa for storing the does address */
        !            59: #define DOES_CODE(cfa) ((Xt *)(((long *)(cfa))[1]))
        !            60: /* this is a special version of DOES_CODE for use in dodoes */
        !            61: #define DOES_CODE1(label)      DOES_CODE(label)
        !            62: 
        !            63: /* the does handler resides between DOES> and the following Forth
        !            64:    code. Since the code-field jumps directly to dodoes, the
        !            65:    does-handler is not needed for the Power architecture */
        !            66: #define DOES_HANDLER_SIZE       8
        !            67: #define MAKE_DOES_HANDLER(addr)   0
        !            68: 
        !            69: /* This makes a code field for a does-defined word. doesp is the
        !            70:    address of the does-code. On the PPC, the code field consists of a
        !            71:    jump to dodoes and the address of the does code */
        !            72: #define MAKE_DOES_CF(cfa,doesp) ({Xt *_cfa = (Xt *)(cfa); \
        !            73:                                    MAKE_CF(_cfa, symbols[DODOES]); \
        !            74:                                    _cfa[1] = (doesp); })
        !            75: #endif

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