1 # Helpers to compute widths of SubX arguments based on their metadata.
2 # /imm8 => 1 byte,
3 # /disp32 => 4 bytes,
4 # and so on.
5
6 == code
7 # instruction effective address register displacement immediate
8 # . op subop mod rm32 base index scale r32
9 # . 1-3 bytes 3 bits 2 bits 3 bits 3 bits 3 bits 2 bits 2 bits 0/1/2/4 bytes 0/1/2/4 bytes
10
11 compute-width: # word: (addr array byte) -> result/eax: int
12 # . prologue
13 55/push-ebp
14 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
15 # . save registers
16 51/push-ecx
17 # eax = word
18 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 8/disp8 . # copy *(ebp+8) to ecx
19 # var ecx: (addr byte) = &word[word->size]
20 8b/copy 0/mod/indirect 0/rm32/eax . . . 1/r32/ecx . . # copy *eax to ecx
21 8d/copy-address 1/mod/*+disp8 4/rm32/sib 0/base/eax 1/index/ecx . 1/r32/ecx 4/disp8 . # copy eax+ecx+4 to ecx
22 # eax = word->data
23 05/add-to-eax 4/imm32
24 # var in/ecx: slice = {eax, ecx}
25 51/push-ecx
26 50/push-eax
27 89/copy 3/mod/direct 1/rm32/ecx . . . 4/r32/esp . . # copy esp to ecx
28 # return compute-width-of-slice(ecx)
29 # . . push args
30 51/push-ecx
31 # . . call
32 e8/call compute-width-of-slice/disp32
33 # . . discard args
34 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
35 $compute-width:end:
36 # . reclaim locals
37 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
38 # . restore registers
39 59/pop-to-ecx
40 # . epilogue
41 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
42 5d/pop-to-ebp
43 c3/return
44
45 compute-width-of-slice: # s: (addr slice) -> result/eax: int
46 # . prologue
47 55/push-ebp
48 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
49 # . save registers
50 51/push-ecx
51 # ecx = s
52 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 8/disp8 . # copy *(ebp+8) to ecx
53 # if (has-metadata?(word, "imm32")) return 4
54 # . eax = has-metadata?(word, "imm32")
55 # . . push args
56 68/push "imm32"/imm32
57 51/push-ecx
58 # . . call
59 e8/call has-metadata?/disp32
60 # . . discard args
61 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
62 # . if (eax != false) return 4
63 3d/compare-eax-and 0/imm32/false
64 b8/copy-to-eax 4/imm32 # ZF is set, so we can overwrite eax now
65 75/jump-if-!= $compute-width-of-slice:end/disp8
66 # if (has-metadata?(word, "disp32")) return 4
67 # . eax = has-metadata?(word, "disp32")
68 # . . push args
69 68/push "disp32"/imm32
70 51/push-ecx
71 # . . call
72 e8/call has-metadata?/disp32
73 # . . discard args
74 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
75 # . if (eax != false) return 4
76 3d/compare-eax-and 0/imm32/false
77 b8/copy-to-eax 4/imm32 # ZF is set, so we can overwrite eax now
78 75/jump-if-!= $compute-width-of-slice:end/disp8
79 # if (has-metadata?(word, "imm16")) return 2
80 # . eax = has-metadata?(word, "imm16")
81 # . . push args
82 68/push "imm16"/imm32
83 51/push-ecx
84 # . . call
85 e8/call has-metadata?/disp32
86 # . . discard args
87 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
88 # . if (eax != false) return 2
89 3d/compare-eax-and 0/imm32/false
90 b8/copy-to-eax 2/imm32 # ZF is set, so we can overwrite eax now
91 75/jump-if-!= $compute-width-of-slice:end/disp8
92 # if (has-metadata?(word, "disp16")) return 2
93 # . eax = has-metadata?(word, "disp16")
94 # . . push args
95 68/push "disp16"/imm32
96 51/push-ecx
97 # . . call
98 e8/call has-metadata?/disp32
99 # . . discard args
100 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
101 # . if (eax != false) return 2
102 3d/compare-eax-and 0/imm32/false
103 b8/copy-to-eax 2/imm32 # ZF is set, so we can overwrite eax now
104 75/jump-if-!= $compute-width-of-slice:end/disp8
105 # otherwise return 1
106 b8/copy-to-eax 1/imm32
107 $compute-width-of-slice:end:
108 # . restore registers
109 59/pop-to-ecx
110 # . epilogue
111 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
112 5d/pop-to-ebp
113 c3/return
114
115 test-compute-width:
116 # . prologue
117 55/push-ebp
118 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
119 $test-compute-width:imm8:
120 # eax = compute-width("0x2/imm8")
121 # . . push args
122 68/push "0x2/imm8"/imm32
123 # . . call
124 e8/call compute-width/disp32
125 # . . discard args
126 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
127 # check-ints-equal(eax, 1, msg)
128 # . . push args
129 68/push "F - test-compute-width: 0x2/imm8"/imm32
130 50/push-eax
131 68/push 1/imm32
132 # . . call
133 e8/call check-ints-equal/disp32
134 # . . discard args
135 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
136 $test-compute-width:imm16:
137 # eax = compute-width("4/imm16")
138 # . . push args
139 68/push "4/imm16"/imm32
140 # . . call
141 e8/call compute-width/disp32
142 # . . discard args
143 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
144 # check-ints-equal(eax, 2, msg)
145 # . . push args
146 68/push "F - test-compute-width: 4/imm16"/imm32
147 50/push-eax
148 68/push 2/imm32
149 # . . call
150 e8/call check-ints-equal/disp32
151 # . . discard args
152 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
153 $test-compute-width:imm32:
154 # eax = compute-width("4/imm32")
155 # . . push args
156 68/push "4/imm32"/imm32
157 # . . call
158 e8/call compute-width/disp32
159 # . . discard args
160 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
161 # check-ints-equal(eax, 4, msg)
162 # . . push args
163 68/push "F - test-compute-width: 4/imm32"/imm32
164 50/push-eax
165 68/push 4/imm32
166 # . . call
167 e8/call check-ints-equal/disp32
168 # . . discard args
169 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
170 $test-compute-width:disp8:
171 # eax = compute-width("foo/disp8")
172 # . . push args
173 68/push "foo/disp8"/imm32
174 # . . call
175 e8/call compute-width/disp32
176 # . . discard args
177 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
178 # check-ints-equal(eax, 1, msg)
179 # . . push args
180 68/push "F - test-compute-width: foo/disp8"/imm32
181 50/push-eax
182 68/push 1/imm32
183 # . . call
184 e8/call check-ints-equal/disp32
185 # . . discard args
186 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 GNU GENERAL PUBLIC LICENSE
Version 3, 29 June 2007
Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
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