src/user/knob/format.c


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#include <stdbool.h>
#include <stdint.h>

bool try_sntoi(const char *s, uint32_t n, uint32_t *out) {
  uint32_t calc = 0;
  for (uint32_t i = 0; i < n; ++i) {
    if ((s[i] < '0') || (s[i] > '9'))
      return false;
    calc = calc * 10 + s[i] - '0';
  }
  *out = calc;
  return true;
}

__attribute__ ((access (write_only, 2)))
void itosz(uint32_t i, char *out) {
  if (!i) {
    *(uint16_t *)out = (uint16_t)'0';
    return;
  }
  bool zero = false;
  for (uint32_t m = 1000000000; m; m /= 10) {
    uint8_t d = (i / m) % 10;
    if (zero)
      *(out++) = d + '0';
    else if (d) {
      zero = true;
      *(out++) = d + '0';
    }
  }
  *out = '\0';
}

const char *const hex_digits = "0123456789abcdef";

__attribute__ ((access (write_only, 2)))
void itosz_h8(uint8_t i, char *out) {
  out[0] = hex_digits[i >> 4];
  out[1] = hex_digits[i & 0xf];
  out[2] = '\0';
}

__attribute__ ((access (write_only, 2)))
void itosz_h32(uint32_t i, char *out) {
  for (uint8_t digit = 0; digit < 8; ++digit)
    out[digit] = hex_digits[(i >> (28 - digit * 4)) & 0xf];
  out[8] = '\0';
}