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Annotation of GNUtools/cc/bi-run.h, revision 1.1

1.1     ! root        1: /* Definitions for Bytecode Interpreter.
        !             2:    Copyright (C) 1993 Free Software Foundation, Inc.
        !             3: 
        !             4: This file is part of GNU CC.
        !             5: 
        !             6: GNU CC is free software; you can redistribute it and/or modify
        !             7: it under the terms of the GNU General Public License as published by
        !             8: the Free Software Foundation; either version 2, or (at your option)
        !             9: any later version.
        !            10: 
        !            11: GNU CC is distributed in the hope that it will be useful,
        !            12: but WITHOUT ANY WARRANTY; without even the implied warranty of
        !            13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
        !            14: GNU General Public License for more details.
        !            15: 
        !            16: You should have received a copy of the GNU General Public License
        !            17: along with GNU CC; see the file COPYING.  If not, write to
        !            18: the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
        !            19: 
        !            20: #define MAXLITERALS 5
        !            21: 
        !            22: struct arityvec
        !            23: {
        !            24:   char ninputs;
        !            25:   char noutputs;
        !            26:   char nliterals;
        !            27:   char literals[MAXLITERALS];
        !            28: };
        !            29: 
        !            30: struct argtype
        !            31: {
        !            32:   int modealign;               /* Argument mode:alignment */
        !            33:   int size;                    /* Argument size, in bytes */
        !            34: };
        !            35: 
        !            36: struct callinfo
        !            37: {
        !            38:   int nargs;                   /* Number of arguments in call */
        !            39:   struct argtype retvaltype;   /* Type of return value */
        !            40:   struct argtype argtypes[1];  /* Argument types */
        !            41: };
        !            42:   
        !            43: /* Structure describing a bytecode function.  If this changes, we also
        !            44:    need to change expand_function_end () in bc-trans.c  */
        !            45: struct bytecode
        !            46: {
        !            47:   int stacksize;               /* Depth required of evaluation stack.  */
        !            48:   int localsize;               /* Size in bytes of local variables.  */
        !            49:   unsigned char *pc0;          /* Initial program counter. */
        !            50:   void **ptrlit;               /* Vector of (relocatable) pointer literals. */
        !            51:   struct callinfo *callinfo;   /* Vector of procedure call type info. */
        !            52: };
        !            53: 
        !            54: 
        !            55: #define INTERP_BPC 8           /* Bits per char */
        !            56: #define INTERP_BPI \
        !            57:   (sizeof (int) * INTERP_BPC)  /* Bits per int */
        !            58: 
        !            59: 
        !            60: #ifndef min
        !            61: #define min(L, R)  ((L) < (R) ? (L) : (R))
        !            62: #endif
        !            63: 
        !            64: 
        !            65: /* bit field operations. */
        !            66: 
        !            67: /* Low (high) mask: int with low (high) N bits set */
        !            68: 
        !            69: #define LM(N)   ((1 << (N)) - 1)
        !            70: #define HM(N)  ((~LM (INTERP_BPI - (N))))
        !            71: 
        !            72: 
        !            73: /* Sign-extend SIZE low bits of VALUE to integer (typeof VALUE)
        !            74:    Signed bitfields are loaded from memory by the sxloadBI instruction,
        !            75:    which first retrieves the bitfield with XFIELD and then sign extends
        !            76:    it to an SItype. */
        !            77: 
        !            78: #define EXTEND(SIZE, VALUE)                                                  \
        !            79:   ({ SUtype value = (SUtype) (VALUE);                                        \
        !            80:     (value & (1 << ((SIZE) - 1)) ? value | ~LM (SIZE) : value); })
        !            81: 
        !            82: 
        !            83: /* Given OFFSET:SIZE for  a bitfield, calculate:
        !            84: 
        !            85:    [1] BYTE_OFFSET  = the byte offset of the bit field.
        !            86:    [2] BIT_OFFSET   = the bit offset of the bit field (less than INTERP_BPC).
        !            87:    [3] NBYTES       = the number of integral bytes in the bit field.
        !            88:    [4] TRAILING_BITS= the number of trailing bits (less than INTERP_BPC).
        !            89: 
        !            90: 
        !            91:    ,        ,        ,        ,        ,    (memory bytes)
        !            92:                     ----------------        (bitfield)
        !            93:    |        |       ||        |    |        (divisions)
        !            94:         ^         ^       ^      ^
        !            95:         |         |       |      |__ [4]  (bits)
        !            96:         |         |       |_________ [3]  (bytes)
        !            97:         |         |_________________ [2]  (bits)
        !            98:         |___________________________ [1]  (bytes)
        !            99: 
        !           100: 
        !           101:    The above applies to BYTE_LOW_ENDIAN machines. In BYTE_BIG_ENDIAN machines, the
        !           102:    bit numbering is reversed (i.e. bit 0 is the sign bit).
        !           103: 
        !           104:    (Alright, so I drew this to keep my tongue in cheek while writing the code below,
        !           105:     not because I'm into ASCII art.) */
        !           106: 
        !           107: 
        !           108: #define BI_PARAMS(OFFSET, SIZE, BYTE_OFFSET, BIT_OFFSET, NBYTES, TRAILING_BITS)                \
        !           109:   { BYTE_OFFSET = (OFFSET) / (INTERP_BPC);                             \
        !           110:     BIT_OFFSET = (OFFSET) % (INTERP_BPC);                              \
        !           111:     NBYTES = ((SIZE) - (INTERP_BPC - (BIT_OFFSET))) / INTERP_BPC;      \
        !           112:     if ((NBYTES) < 0 || ((NBYTES) > 64))                               \
        !           113:       NBYTES = 0;                                                      \
        !           114:     if ((SIZE) + (BIT_OFFSET) <= INTERP_BPC)                           \
        !           115:       TRAILING_BITS = 0;                                               \
        !           116:     else                                                               \
        !           117:       TRAILING_BITS = ((SIZE) - (INTERP_BPC - (BIT_OFFSET))) % INTERP_BPC; }
        !           118: 
        !           119: 
        !           120: /* SHIFT_IN_BITS retrieves NBITS bits from SOURCE and shifts into
        !           121:    DEST. The bit field starts OFFSET bits into SOURCE.
        !           122: 
        !           123:    OR_IN_BITS copies the NBITS low bits from VALUE into a the bitfield in
        !           124:    DEST offset by OFFSET bits. */
        !           125: 
        !           126: 
        !           127: #ifdef BYTES_BIG_ENDIAN
        !           128: 
        !           129: #define SHIFT_IN_BITS(DEST, SOURCE, OFFSET, NBITS)             \
        !           130:   (DEST = ((DEST) << (NBITS))                                  \
        !           131:    | (LM ((NBITS))                                             \
        !           132:       & ((SOURCE) >> (INTERP_BPC - (OFFSET) - (NBITS)))))
        !           133: 
        !           134: #define OR_IN_BITS(DEST, VALUE, OFFSET, NBITS)                 \
        !           135:   (DEST = ((DEST) & ~(LM ((NBITS)) << (INTERP_BPC - (OFFSET) - (NBITS))))      \
        !           136:    | (((VALUE) & LM ((NBITS))) << (INTERP_BPC - (OFFSET) - (NBITS))))
        !           137: 
        !           138: #else
        !           139: 
        !           140: #define SHIFT_IN_BITS(DEST, SOURCE, OFFSET, NBITS)             \
        !           141:   (DEST = ((DEST) << (NBITS))                                  \
        !           142:    | (LM ((NBITS))                                             \
        !           143:       & ((SOURCE) >> (OFFSET))))
        !           144: 
        !           145: #define OR_IN_BITS(DEST, VALUE, OFFSET, NBITS)                 \
        !           146:   (DEST = ((DEST) & ~(LM ((NBITS)) << (OFFSET)))               \
        !           147:    | (((VALUE) & LM ((NBITS))) << (OFFSET)))
        !           148: 
        !           149: #endif
        !           150: 
        !           151: 
        !           152: /* Procedure call; arguments are a pointer to the function to be called,
        !           153:    a pointer to a place to store the return value, a pointer to a vector
        !           154:    describing the type of procedure call, and the interpreter's stack pointer,
        !           155:    which will point to the first of the arguments at this point.  */
        !           156: 
        !           157: #define CALL(FUNC, CALLDESC, RETVAL, SP) __call(FUNC, CALLDESC, RETVAL, SP)
        !           158: 
        !           159: 
        !           160: /* Procedure return; arguments are a pointer to the calldesc for this
        !           161:    function, and a pointer to the place where the value to be returned
        !           162:    may be found.  Generally the MACHARGS above contain a machine dependent
        !           163:    cookie that is used to determine where to jump to.  */
        !           164: 
        !           165: #define PROCRET(CALLDESC, RETVAL) return

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