semihosting.hpp

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#pragma once
#include "../microfmt.hpp"
 
namespace microfmt {
 
class MICROFMT_API_CLASS semihosting_sink {
public:
  constexpr semihosting_sink() noexcept = default;
 
  static void write(void *, microfmt::string_view sv) noexcept {
    if (sv.empty()) {
      return;
    }
 
    for (char c : sv) {
#if defined(__aarch64__)
      register uint64_t reg_sysnum __asm__("x0") = 0x03; // SYS_WRITEC operation code
      register const char *reg_ptr __asm__("x1") = &c;   // Pointer to the character
 
      __asm__ volatile("hlt #0xf000" : "+r"(reg_sysnum) : "r"(reg_ptr) : "memory", "cc");
#elif defined(__arm__) || defined(__thumb__)
      register uint32_t reg_sysnum __asm__("r0") = 0x03; // SYS_WRITEC operation code
      register const char *reg_ptr __asm__("r1") = &c;   // Pointer to the character
 
      __asm__ volatile("bkpt #0xab" : "+r"(reg_sysnum) : "r"(reg_ptr) : "memory", "cc");
#else
#error "Unsupported architecture for semihosting_sink"
#endif
    }
  }
 
  [[nodiscard]] constexpr sink as_sink() const noexcept {
    return sink{.ctx = nullptr, .write_fn = &semihosting_sink::write};
  }
};
 
} // namespace microfmt