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use usize to determine size of roc str

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Folkert 2021-01-25 17:11:56 +01:00
parent 4bd84f4b6f
commit 257985496b
1 changed files with 25 additions and 12 deletions
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37
compiler/builtins/bitcode/src/str.zig
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@ -12,6 +12,20 @@ const InPlace = packed enum(u8) {
Clone,
};
const small_string_size = 2 * @sizeOf(usize);
const blank_small_string: [16]u8 = init_blank_small_string(small_string_size);
fn init_blank_small_string(comptime n: usize) [n]u8 {
var prime_list: [n]u8 = undefined;
var i = 0;
while (i < n) : (i += 1) {
prime_list[i] = 0;
}
return prime_list;
}
pub const RocStr = extern struct {
str_bytes: ?[*]u8,
str_len: usize,
@ -34,17 +48,17 @@ pub const RocStr = extern struct {
return result;
}
pub fn initBig(allocator: *Allocator, comptime T: type, in_place: InPlace, number_of_chars: u64) RocStr {
const length = @sizeOf(T) + number_of_chars;
var new_bytes: []T = allocator.alloc(T, length) catch unreachable;
pub fn initBig(allocator: *Allocator, in_place: InPlace, number_of_chars: u64) RocStr {
const length = @sizeOf(usize) + number_of_chars;
var new_bytes: []usize = allocator.alloc(usize, length) catch unreachable;
if (in_place == InPlace.InPlace) {
new_bytes[0] = @intCast(T, number_of_chars);
new_bytes[0] = @intCast(usize, number_of_chars);
} else {
new_bytes[0] = std.math.minInt(T);
new_bytes[0] = std.math.minInt(usize);
}
var first_element = @ptrCast([*]align(@alignOf(T)) u8, new_bytes);
var first_element = @ptrCast([*]align(@alignOf(usize)) u8, new_bytes);
first_element += @sizeOf(usize);
return RocStr{
@ -55,18 +69,17 @@ pub const RocStr = extern struct {
// allocate space for a (big or small) RocStr, but put nothing in it yet
pub fn allocate(allocator: *Allocator, comptime T: type, result_in_place: InPlace, number_of_chars: usize) RocStr {
const small_str_bytes = 2 * @sizeOf(T);
const result_is_big = number_of_chars >= small_str_bytes;
const result_is_big = number_of_chars >= small_string_size;
if (result_is_big) {
return RocStr.initBig(allocator, T, result_in_place, number_of_chars);
return RocStr.initBig(allocator, result_in_place, number_of_chars);
} else {
var t = [16]u8{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
var t = blank_small_string;
const mask: u8 = 0b1000_0000;
const final_byte = @truncate(u8, number_of_chars) | mask;
t[small_str_bytes - 1] = final_byte;
t[small_string_size - 1] = final_byte;
return @bitCast(RocStr, t);
}
@ -141,7 +154,7 @@ pub const RocStr = extern struct {
// just return the bytes
return str;
} else {
var new_str = RocStr.initBig(allocator, T, in_place, str.str_len);
var new_str = RocStr.initBig(allocator, in_place, str.str_len);
var old_bytes: [*]u8 = @ptrCast([*]u8, str.str_bytes);
var new_bytes: [*]u8 = @ptrCast([*]u8, new_str.str_bytes);