1 files changed, 98 insertions, 0 deletions
diff --git a/subprojects/exess/src/year.c b/subprojects/exess/src/year.c
new file mode 100644
index 00000000..e268ff80
--- /dev/null
+++ b/subprojects/exess/src/year.c
@@ -0,0 +1,98 @@
+/*
+  Copyright 2019-2021 David Robillard <d@drobilla.net>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#include "date_utils.h"
+#include "int_math.h"
+#include "macros.h"
+#include "read_utils.h"
+#include "write_utils.h"
+
+#include "exess/exess.h"
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+ExessResult
+read_year_number(int16_t* const out, const char* const str)
+{
+  *out = 0;
+
+  // Read leading sign if present
+  size_t i    = 0;
+  int    sign = 1;
+  if (str[i] == '-') {
+    sign = -1;
+    ++i;
+  }
+
+  // Read digits
+  uint64_t    magnitude = 0;
+  ExessResult r         = exess_read_ulong(&magnitude, str + i);
+  if (r.status > EXESS_EXPECTED_END) {
+    return result(r.status, i + r.count);
+  }
+
+  i += r.count;
+
+  if (sign > 0) {
+    if (magnitude > (uint16_t)INT16_MAX) {
+      return result(EXESS_OUT_OF_RANGE, i);
+    }
+
+    *out = (int16_t)magnitude;
+  } else {
+    const uint16_t min_magnitude = (uint16_t)(-(INT16_MIN + 1)) + 1;
+    if (magnitude > min_magnitude) {
+      return result(EXESS_OUT_OF_RANGE, i);
+    }
+
+    if (magnitude == min_magnitude) {
+      *out = INT16_MIN;
+    } else {
+      *out = (int16_t)-magnitude;
+    }
+  }
+
+  return result(r.count >= 4 ? EXESS_SUCCESS : EXESS_EXPECTED_DIGIT, i);
+}
+
+ExessResult
+write_year_number(const int16_t value, const size_t buf_size, char* const buf)
+{
+  const uint32_t abs_year    = (uint32_t)abs(value);
+  const uint8_t  n_digits    = exess_num_digits(abs_year);
+  const bool     is_negative = value < 0;
+
+  if (!buf) {
+    return result(EXESS_SUCCESS, is_negative + MAX(4u, n_digits));
+  }
+
+  // Write sign
+  size_t i = 0;
+  if (is_negative) {
+    i += write_char('-', buf_size, buf, i);
+  }
+
+  // Write leading zeros to ensure we have at least 4 year digits
+  for (size_t j = n_digits; j < 4; ++j) {
+    i += write_char('0', buf_size, buf, i);
+  }
+
+  const ExessResult yr = exess_write_uint(abs_year, buf_size - i, buf + i);
+
+  return end_write(yr.status, buf_size, buf, i + yr.count);
+}