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114 lines
3.4 KiB
114 lines
3.4 KiB
#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <stdbool.h>
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#include <limits.h>
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#include "view.h"
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#define S_PTR_MASK (0xcafebeef00000000ul) /* XXX: Should this frob the high or end parts of the pointer? We'll go with high? */
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#define $mixin __attribute__((__gnu_inline__, __always_inline__, __artificial__)) inline
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#define $nullchk(ptr, or) ({ __auto_type _$p = (ptr); \
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__builtin_expect(_$p == NULL, false) ? ({ or; }),NULL : _$p; })
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typedef uint8_t byte_t;
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__attribute__((packed))
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struct string_metadata {
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bool is_owned : 1; // was the string malloc()'d
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bool has_nul : 1; // does this string have a nul terminator
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};
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struct string_data {
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struct string_metadata meta;
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uintptr_t ptr_frob;
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struct /*_Alignas(struct string_view)*/ {
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size_t len;
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char ptr[];
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} __attribute__((aligned(_Alignof(struct string_view)))); //__attribute__((align(struct string_view)));
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};
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#define _s_frob_pointer_(p, f) ((/*__typeof((p))*/void*) (((uintptr_t)(p)) ^ ((uintptr_t)(f))))
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__attribute__((const))
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$mixin static void* _s_frob_pointer(void* p)
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{
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return _s_frob_pointer_(p, S_PTR_MASK);
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}
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#define _s_frob_pointer(p) _s_frob_pointer_((p), S_PTR_MASK)
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#define $frob(v, w) _s_frob_pointer_((v), (w))
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static inline struct string* _s_frob(struct string_data* restrict d) {
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return (struct string*) _s_frob_pointer(d->ptr);
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}
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static inline struct string_data* _s_unfrob(struct string *restrict ptr) {
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// static const off64_t O_this = offsetof(struct string_data, ptr);
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struct string_data* restrict base = (void*)((byte_t*)_s_frob_pointer(ptr)) - offsetof(struct string_data, ptr);
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uintptr_t frob = base->ptr_frob;
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if(frob != ((uintptr_t)_s_frob_pointer(base))) return NULL; //XXX: TODO: Is this valid? Probably, since struct string_data will only ever be heap-allocated.
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return base;
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}
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$mixin static char* _s_str(struct string_data* restrict data) { return data->ptr; }
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$mixin extern struct string_data* _s_data(char* str, bool check) {
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struct string_data* sd = (struct string_data*)( ((byte_t*)str) - offsetof(struct string_data, ptr) );
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if(__builtin_constant_p(check) && !check) return sd;
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else if(check && sd->ptr_frob != ((uintptr_t)_s_frob_pointer(sd))) return NULL;
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else return sd;
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}
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static struct string_data* _s_data(char* str, bool check) {
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static const size_t O_base = offsetof(struct string_data, ptr);
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struct string_data* sd = (struct string_data*)( ((byte_t*)str) - O_base );
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if(__builtin_constant_p(check) && !check) return sd;
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else if(check && sd->ptr_frob != ((uintptr_t)_s_frob_pointer(sd))) return NULL;
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else return sd;
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}
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__attribute__((pure))
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str_info_t s_get_info(view_t str)
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{
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return _s_data($nullchk(str.ptr, return NULL), true);
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}
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__attribute__((pure))
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view_t s_get_str(str_info_t data)
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{
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return (view_t) {
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.len = data->len,
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.ptr = data->ptr,
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};
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}
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__attribute__((cold))
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static size_t _sv_copy_manual(size_t sz, char buffer[restrict static sz], view_t view)
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{
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size_t i=0;
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for(;i< (sz-1) && i<view.len;i++)
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{
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buffer[i] = view.ptr[i];
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}
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buffer[i] = 0;
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return view.len+1;
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}
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size_t sv_copy_to(size_t sz, char buffer[restrict static sz], view_t view)
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{
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if(__builtin_expect(view.len <= INT_MAX, true))
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return (size_t)snprintf(buffer, sz, "%.*s", (int)view.len, view.ptr);
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else {
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// Manual implementation, for views longer than INT_MAX
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//XXX: TODO: Ensure return value follows the same construct.
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return _sv_copy_manual(sz, buffer, view);
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}
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}
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