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Annotation of gforth/power.h, revision 1.2

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: #warning If you get assembly errors, here is the reason why
1.2     ! anton      21: #define FLUSH_ICACHE(addr,size)   asm("icbi (%0); isync"::"b"(addr))
1.1       anton      22: /* this assumes size=4 */
                     23: /* the mnemonics are for the PPC and the syntax is a wild guess; for
                     24:    Power the mnemonic for the isync instruction is "ics" and I have
                     25:    not found an equivalent for the icbi instruction in my reference.
                     26: */
1.2     ! anton      27: 
        !            28: #ifdef DIRECT_THREADED
        !            29: #warning Direct threading for Power has not been tested
1.1       anton      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