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1/* This is a simple version of setjmp and longjmp.
2
3 Nick Clifton, Cygnus Solutions, 13 June 1997. */
4
5/* ANSI concatenation macros. */
6#define CONCAT(a, b) CONCAT2(a, b)
7#define CONCAT2(a, b) a##b
8
9#ifndef __USER_LABEL_PREFIX__
10#error __USER_LABEL_PREFIX__ not defined
11#endif
12
13#define SYM(x) CONCAT (__USER_LABEL_PREFIX__, x)
14
15#ifdef __ELF__
16#define TYPE(x) .type SYM(x),function
17#define SIZE(x) .size SYM(x), . - SYM(x)
18#else
19#define TYPE(x)
20#define SIZE(x)
21#endif
22
23/* Arm/Thumb interworking support:
24
25 The interworking scheme expects functions to use a BX instruction
26 to return control to their parent. Since we need this code to work
27 in both interworked and non-interworked environments as well as with
28 older processors which do not have the BX instruction we do the
29 following:
30 Test the return address.
31 If the bottom bit is clear perform an "old style" function exit.
32 (We know that we are in ARM mode and returning to an ARM mode caller).
33 Otherwise use the BX instruction to perform the function exit.
34
35 We know that we will never attempt to perform the BX instruction on
36 an older processor, because that kind of processor will never be
37 interworked, and a return address with the bottom bit set will never
38 be generated.
39
40 In addition, we do not actually assemble the BX instruction as this would
41 require us to tell the assembler that the processor is an ARM7TDMI and
42 it would store this information in the binary. We want this binary to be
43 able to be linked with binaries compiled for older processors however, so
44 we do not want such information stored there.
45
46 If we are running using the APCS-26 convention however, then we never
47 test the bottom bit, because this is part of the processor status.
48 Instead we just do a normal return, since we know that we cannot be
49 returning to a Thumb caller - the Thumb does not support APCS-26.
50
51 Function entry is much simpler. If we are compiling for the Thumb we
52 just switch into ARM mode and then drop through into the rest of the
53 function. The function exit code will take care of the restore to
54 Thumb mode.
55
56 For Thumb-2 do everything in Thumb mode. */
57
58#ifdef __APCS_26__
59#define RET movs pc, lr
60#elif defined(__thumb2__)
61#define RET bx lr
62#else
63#define RET tst lr, #1; \
64 moveq pc, lr ; \
65.word 0xe12fff1e /* bx lr */
66#endif
67
68#ifdef __thumb2__
69.macro COND where when
70 i\where \when
71.endm
72#else
73.macro COND where when
74.endm
75#endif
76
77#if defined(__thumb2__)
78.syntax unified
79.macro MODE
80 .thumb
81 .thumb_func
82.endm
83.macro PROLOGUE name
84.endm
85
86#elif defined(__thumb__)
87#define MODE .thumb_func
88.macro PROLOGUE name
89 .code 16
90 bx pc
91 nop
92 .code 32
93SYM (.arm_start_of.\name):
94.endm
95#else /* Arm */
96#define MODE .code 32
97.macro PROLOGUE name
98.endm
99#endif
100
101.macro FUNC_START name
102 .text
103 .align 2
104 MODE
105 .globl SYM (\name)
106 TYPE (\name)
107SYM (\name):
108 PROLOGUE \name
109.endm
110
111.macro FUNC_END name
112 RET
113 SIZE (\name)
114.endm
115
116/* --------------------------------------------------------------------
117 int setjmp (jmp_buf);
118 -------------------------------------------------------------------- */
119
120 FUNC_START setjmp
121
122 /* Save all the callee-preserved registers into the jump buffer. */
123#ifdef __thumb2__
124 stmea a1!, { v1-v7, fp, ip, lr }
125 str sp, [a1],#+4
126#else
127 stmea a1!, { v1-v7, fp, ip, sp, lr }
128#endif
129
130#if 0 /* Simulator does not cope with FP instructions yet. */
131#ifndef __SOFTFP__
132 /* Save the floating point registers. */
133 sfmea f4, 4, [a1]
134#endif
135#endif
136 /* When setting up the jump buffer return 0. */
137 mov a1, #0
138
139 FUNC_END setjmp
140
141/* --------------------------------------------------------------------
142 volatile void longjmp (jmp_buf, int);
143 -------------------------------------------------------------------- */
144
145 FUNC_START longjmp
146
147 /* If we have stack extension code it ought to be handled here. */
148
149 /* Restore the registers, retrieving the state when setjmp() was called. */
150#ifdef __thumb2__
151 ldmfd a1!, { v1-v7, fp, ip, lr }
152 ldr sp, [a1],#+4
153#else
154 ldmfd a1!, { v1-v7, fp, ip, sp, lr }
155#endif
156
157#if 0 /* Simulator does not cope with FP instructions yet. */
158#ifndef __SOFTFP__
159 /* Restore floating point registers as well. */
160 lfmfd f4, 4, [a1]
161#endif
162#endif
163 /* Put the return value into the integer result register.
164 But if it is zero then return 1 instead. */
165 movs a1, a2
166#ifdef __thumb2__
167 it eq
168#endif
169 moveq a1, #1
170
171 FUNC_END longjmp
172