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1.1 root 1: /* Definitions for Bytecode Interpreter.
1.1.1.2 root 2: Copyright (C) 1993, 1994 Free Software Foundation, Inc.
1.1 root 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
1.1.1.3 ! root 18: the Free Software Foundation, 59 Temple Place - Suite 330,
! 19: Boston, MA 02111-1307, USA. */
1.1 root 20:
21: #define MAXLITERALS 5
22:
23: struct arityvec
24: {
25: char ninputs;
26: char noutputs;
27: char nliterals;
28: char literals[MAXLITERALS];
29: };
30:
31: struct argtype
32: {
33: int modealign; /* Argument mode:alignment */
34: int size; /* Argument size, in bytes */
35: };
36:
37: struct callinfo
38: {
39: int nargs; /* Number of arguments in call */
40: struct argtype retvaltype; /* Type of return value */
41: struct argtype argtypes[1]; /* Argument types */
42: };
43:
44: /* Structure describing a bytecode function. If this changes, we also
45: need to change expand_function_end () in bc-trans.c */
46: struct bytecode
47: {
48: int stacksize; /* Depth required of evaluation stack. */
49: int localsize; /* Size in bytes of local variables. */
50: unsigned char *pc0; /* Initial program counter. */
51: void **ptrlit; /* Vector of (relocatable) pointer literals. */
52: struct callinfo *callinfo; /* Vector of procedure call type info. */
53: };
54:
55:
56: #define INTERP_BPC 8 /* Bits per char */
57: #define INTERP_BPI \
58: (sizeof (int) * INTERP_BPC) /* Bits per int */
59:
60:
61: #ifndef min
62: #define min(L, R) ((L) < (R) ? (L) : (R))
63: #endif
64:
65:
66: /* bit field operations. */
67:
68: /* Low (high) mask: int with low (high) N bits set */
69:
70: #define LM(N) ((1 << (N)) - 1)
71: #define HM(N) ((~LM (INTERP_BPI - (N))))
72:
73:
74: /* Sign-extend SIZE low bits of VALUE to integer (typeof VALUE)
75: Signed bitfields are loaded from memory by the sxloadBI instruction,
76: which first retrieves the bitfield with XFIELD and then sign extends
77: it to an SItype. */
78:
79: #define EXTEND(SIZE, VALUE) \
80: ({ SUtype value = (SUtype) (VALUE); \
81: (value & (1 << ((SIZE) - 1)) ? value | ~LM (SIZE) : value); })
82:
83:
84: /* Given OFFSET:SIZE for a bitfield, calculate:
85:
86: [1] BYTE_OFFSET = the byte offset of the bit field.
87: [2] BIT_OFFSET = the bit offset of the bit field (less than INTERP_BPC).
88: [3] NBYTES = the number of integral bytes in the bit field.
89: [4] TRAILING_BITS= the number of trailing bits (less than INTERP_BPC).
90:
91:
92: , , , , , (memory bytes)
93: ---------------- (bitfield)
94: | | || | | (divisions)
95: ^ ^ ^ ^
96: | | | |__ [4] (bits)
97: | | |_________ [3] (bytes)
98: | |_________________ [2] (bits)
99: |___________________________ [1] (bytes)
100:
101:
102: The above applies to BYTE_LOW_ENDIAN machines. In BYTE_BIG_ENDIAN machines, the
103: bit numbering is reversed (i.e. bit 0 is the sign bit).
104:
1.1.1.3 ! root 105: (All right, so I drew this to keep my tongue in cheek while writing the code below,
1.1 root 106: not because I'm into ASCII art.) */
107:
108:
109: #define BI_PARAMS(OFFSET, SIZE, BYTE_OFFSET, BIT_OFFSET, NBYTES, TRAILING_BITS) \
110: { BYTE_OFFSET = (OFFSET) / (INTERP_BPC); \
111: BIT_OFFSET = (OFFSET) % (INTERP_BPC); \
112: NBYTES = ((SIZE) - (INTERP_BPC - (BIT_OFFSET))) / INTERP_BPC; \
113: if ((NBYTES) < 0 || ((NBYTES) > 64)) \
114: NBYTES = 0; \
115: if ((SIZE) + (BIT_OFFSET) <= INTERP_BPC) \
116: TRAILING_BITS = 0; \
117: else \
118: TRAILING_BITS = ((SIZE) - (INTERP_BPC - (BIT_OFFSET))) % INTERP_BPC; }
119:
120:
121: /* SHIFT_IN_BITS retrieves NBITS bits from SOURCE and shifts into
122: DEST. The bit field starts OFFSET bits into SOURCE.
123:
124: OR_IN_BITS copies the NBITS low bits from VALUE into a the bitfield in
125: DEST offset by OFFSET bits. */
126:
127:
128: #define SHIFT_IN_BITS(DEST, SOURCE, OFFSET, NBITS) \
129: (DEST = ((DEST) << (NBITS)) \
130: | (LM ((NBITS)) \
1.1.1.3 ! root 131: & ((SOURCE) \
! 132: >> (BYTES_BIG_ENDIAN \
! 133: ? (INTERP_BPC - (OFFSET) - (NBITS)) \
! 134: : (OFFSET)))))
1.1 root 135:
136: #define OR_IN_BITS(DEST, VALUE, OFFSET, NBITS) \
1.1.1.3 ! root 137: (DEST = ((DEST) & ~(LM ((NBITS)) \
! 138: << (BIG_ENDIAN \
! 139: ? (INTERP_BPC - (OFFSET) - (NBITS)) \
! 140: : (OFFSET))) \
! 141: | (((VALUE) & LM ((NBITS))) \
! 142: << (BIG_ENDIAN \
! 143: ? (INTERP_BPC - (OFFSET) - (NBITS)) \
! 144: : (OFFSET)))))
1.1 root 145:
146: /* Procedure call; arguments are a pointer to the function to be called,
147: a pointer to a place to store the return value, a pointer to a vector
148: describing the type of procedure call, and the interpreter's stack pointer,
149: which will point to the first of the arguments at this point. */
150:
151: #define CALL(FUNC, CALLDESC, RETVAL, SP) __call(FUNC, CALLDESC, RETVAL, SP)
152:
153:
154: /* Procedure return; arguments are a pointer to the calldesc for this
155: function, and a pointer to the place where the value to be returned
156: may be found. Generally the MACHARGS above contain a machine dependent
157: cookie that is used to determine where to jump to. */
158:
159: #define PROCRET(CALLDESC, RETVAL) return
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