Mercurial > hg > CbC > CbC_gcc
annotate gcc/config/stormy16/stormy-abi @ 55:77e2b8dfacca gcc-4.4.5
update it from 4.4.3 to 4.5.0
| author | ryoma <e075725@ie.u-ryukyu.ac.jp> |
|---|---|
| date | Fri, 12 Feb 2010 23:39:51 +0900 |
| parents | a06113de4d67 |
| children | 04ced10e8804 |
| rev | line source |
|---|---|
| 0 | 1 xStormy16 ABI |
| 2 ************ | |
| 3 | |
| 4 !!!!! NOTE !!!!! | |
| 5 This document is a draft and is subject to change. | |
| 6 !!!!! NOTE !!!!! | |
| 7 | |
| 8 This part of the file describes the conventions required to write | |
| 9 ELF object files that are link-compatible with the ones produced | |
| 10 by the GNU toolchains. | |
| 11 | |
| 12 Bit and Byte Ordering | |
| 13 ===================== | |
| 14 | |
| 15 This implementation is little-endian. Bits are numbered starting | |
| 16 from 0 being the LSB. | |
| 17 | |
| 18 In this document, 'word' means 16 bits. | |
| 19 | |
| 20 Calling Sequence | |
| 21 ================ | |
| 22 | |
| 23 The registers are allocated as follows: | |
| 24 | |
| 25 Register Purpose | |
| 26 ------------------------------------------------------------------- | |
| 27 r0, r1 Call-volatile. May be changed during the execution | |
| 28 of a call instruction. | |
| 29 r2 through r7 Argument passing; call-clobbered. | |
| 30 r8, r9 Call-volatile. May be changed during the execution | |
| 31 of a call instruction. | |
| 32 r10 through r13 Call-saved. | |
| 33 r14 Program status word. | |
| 34 r15 Stack pointer. | |
| 35 | |
| 36 | |
| 37 Scalar values are returned in register r2-r7 if the value fits. | |
| 38 Otherwise, a pointer is passed as a 'hidden' first argument and | |
| 39 the return value is placed there. | |
| 40 | |
| 41 Arguments are passed in registers starting in r2, then on the stack. | |
| 42 Arguments of size not a multiple of a word are padded to whole words. | |
| 43 If an argument would otherwise be passed partially in registers, and | |
| 44 partially on the stack, the whole of it is passed on the stack. The | |
| 45 last argument is pushed on the stack first. | |
| 46 | |
| 47 After a procedure's arguments are pushed on the stack, | |
| 48 the return address is pushed on the stack, as if by the call | |
| 49 instruction. The return address is on the top of the stack when | |
| 50 a procedure is called. | |
| 51 | |
| 52 Objects whose size is a multiple of 16 bits are aligned to a 16-bit | |
| 53 boundary. | |
| 54 | |
| 55 Pointers are 16 bits, referencing addresses between 0 and 0xFFFF. | |
| 56 | |
| 57 Procedure pointers are also implemented as 16-bit pointers. | |
| 58 | |
| 59 Variable Argument Functions | |
| 60 =========================== | |
| 61 | |
| 62 The C type 'va_list' is implemented as a structure, as follows: | |
| 63 | |
| 64 struct { | |
| 65 char *base; | |
| 66 unsigned count; | |
| 67 } | |
| 68 | |
| 69 Both fields are 16 bits. An argument of size N bytes | |
| 70 (N will be even) is accessed as if by the following code: | |
| 71 | |
| 72 char *result; | |
| 73 /* count = #bytes non-variable arguments */ | |
| 74 /* 12 = #bytes for register arguments */ | |
| 75 if (count + N > 12) | |
| 76 { | |
| 77 if (count < 12) | |
| 78 count = 12; | |
| 79 result = base - (count + N - 12 + 4); | |
| 80 } | |
| 81 else | |
| 82 { | |
| 83 result = base + count; | |
| 84 } | |
| 85 count += N; | |
| 86 /* The argument is at `*result'. */ | |
| 87 | |
| 88 | |
| 89 One implementation of this is if a variadic function first | |
| 90 pushes registers 2 through 7 in sequence at entry, and | |
| 91 sets 'base' to the address of the first word pushed, | |
| 92 producing a stack that appears like: | |
| 93 | |
| 94 SP -> | |
| 95 [other data] | |
| 96 r7 | |
| 97 r6 | |
| 98 r5 | |
| 99 r4 | |
| 100 r3 | |
| 101 count-> r2 | |
| 102 Return address (two words) | |
| 103 7th procedure parameter word | |
| 104 8th procedure parameter word | |
| 105 ... | |
| 106 last procedure parameter word | |
| 107 | |
| 108 and initializes 'count' to be the number of bytes of non-variable | |
| 109 arguments to the function. | |
| 110 | |
| 111 ELF File Format | |
| 112 =============== | |
| 113 | |
| 114 ELF file header | |
| 115 --------------- | |
| 116 | |
| 117 xStormy16 ELF files are distinguished by the value EM_XSTORMY16 in | |
| 118 the e_machine field of the ELF file header: | |
| 119 | |
| 120 #define EM_XSTORMY16 0xad45 | |
| 121 | |
| 122 DWARF Register Number Mapping | |
| 123 ----------------------------- | |
| 124 | |
| 125 Registers r0 through r15 are mapped to numbers 0 through 15. | |
| 126 | |
| 127 Relocations | |
| 128 ----------- | |
| 129 | |
| 130 RELA relocs are used exclusively. The relocation types defined are: | |
| 131 | |
| 132 Name Value Field Calculation Overflow | |
| 133 ---------------------------------------------------------------- | |
| 134 R_XSTORMY16_NONE 0 none none none | |
| 135 R_XSTORMY16_32 1 32 S + A none | |
| 136 R_XSTORMY16_16 2 16 S + A either | |
| 137 R_XSTORMY16_8 3 8 S + A unsigned | |
| 138 R_XSTORMY16_PC32 4 32 S + A - P none | |
| 139 R_XSTORMY16_PC16 5 16 S + A - P signed | |
| 140 R_XSTORMY16_PC8 6 8 S + A - P signed | |
| 141 R_XSTORMY16_REL_12 7 16:12:0 S + A - P signed | |
| 142 R_XSTORMY16_24 8 32:23:1 (S + A) >> 1 unsigned | |
| 143 R_XSTORMY16_FPTR16 9 16 S + A either | |
| 144 R_XSTORMY16_LO16 10 16 S + A none | |
| 145 R_XSTORMY16_HI16 11 32:16:16 S + A none | |
| 146 R_XSTORMY16_12 12 16:12:0 S + A signed | |
| 147 R_XSTORMY16_GNU_VTINHERIT 128 n/a n/a n/a | |
| 148 R_XSTORMY16_GNU_VTENTRY 129 n/a n/a n/a | |
| 149 | |
| 150 In the 'Field' column, the first number indicates whether the | |
| 151 relocation refers to a byte, word or doubleword. The second number, | |
| 152 if any, indicates the size of the bit-field into which the relocation | |
| 153 is to occur (and also the size for overflow checking). The third | |
| 154 number indicates the first bit of the bit-field in the word or | |
| 155 doubleword, counting the LSB as bit 0. | |
| 156 | |
| 157 In the 'Calculation' column, 'S' is the value of the symbol to which | |
| 158 the reloc refers, 'A' is the addend, and 'P' represents the place of | |
| 159 the storage unit being relocated. | |
| 160 | |
| 161 In the 'Overflow' column, 'none' means that any overflow of the | |
| 162 computation performed in the 'Calculation' column is ignored. | |
| 163 'signed' means that the overflow is only reported if it happens when | |
| 164 the values are treated as signed quantities. 'unsigned' is the same, | |
| 165 except that the values are treated as unsigned quantities. 'either' | |
| 166 means that overflow is reported for either signed or unsigned | |
| 167 overflow. | |
|
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77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
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168 |
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77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
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169 |
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77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
0
diff
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170 Copyright (C) 2001, 2002, 2003, 2005 Free Software Foundation, Inc. |
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77e2b8dfacca
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ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
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171 |
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77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
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172 Copying and distribution of this file, with or without modification, |
|
77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
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173 are permitted in any medium without royalty provided the copyright |
|
77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
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174 notice and this notice are preserved. |