60 lines
1.6 KiB
C
60 lines
1.6 KiB
C
/* va_list.c - tinycc support for va_list on X86_64 */
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#if defined __x86_64__
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/* Avoid include files, they may not be available when cross compiling */
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extern void* memset(void* s, int c, __SIZE_TYPE__ n);
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extern void abort(void);
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/* This should be in sync with our include/stdarg.h */
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enum __va_arg_type { __va_gen_reg, __va_float_reg, __va_stack };
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/* GCC compatible definition of va_list. */
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typedef struct {
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unsigned int gp_offset;
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unsigned int fp_offset;
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union {
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unsigned int overflow_offset;
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char* overflow_arg_area;
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};
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char* reg_save_area;
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} __va_list_struct;
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void __va_start(__va_list_struct* ap, void* fp) {
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memset(ap, 0, sizeof(__va_list_struct));
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*ap = *(__va_list_struct*)((char*)fp - 16);
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ap->overflow_arg_area = (char*)fp + ap->overflow_offset;
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ap->reg_save_area = (char*)fp - 176 - 16;
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}
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void* __va_arg(__va_list_struct* ap, enum __va_arg_type arg_type, int size, int align) {
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size = (size + 7) & ~7;
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align = (align + 7) & ~7;
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switch (arg_type) {
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case __va_gen_reg:
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if (ap->gp_offset + size <= 48) {
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ap->gp_offset += size;
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return ap->reg_save_area + ap->gp_offset - size;
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}
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goto use_overflow_area;
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case __va_float_reg:
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if (ap->fp_offset < 128 + 48) {
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ap->fp_offset += 16;
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return ap->reg_save_area + ap->fp_offset - 16;
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}
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size = 8;
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goto use_overflow_area;
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case __va_stack:
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use_overflow_area:
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ap->overflow_arg_area += size;
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ap->overflow_arg_area = (char*)((long long)(ap->overflow_arg_area + align - 1) & -align);
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return ap->overflow_arg_area - size;
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default: /* should never happen */
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abort();
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}
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}
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#endif
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