ufmt-stdio

Minimal printing facilities for ufmt

Supported platforms:

wasm via wasm-bindings;
mos microprocessors via linking putchar;
riscv32 via esp-* features (see details in Features section) or being no-op otherwise;
All other platforms are built upon standard C library write function.

esp-uart - Enables UART writer on riscv32 targets. Mutually exclusive with esp-jtag. Requires user to provide symbols:
- ESP_UART_ADDR (e.g. on ESP32-C3 it is #[no_mangle] static ESP_UART_ADDR: usize = 0x40000068).
esp-jtag - Enables JTAG writer on riscv32 targets. Mutually exclusive with esp-jtag. Requires user to provide symbols:
- SERIAL_JTAG_FIFO_REG (e.g. on ESP32-C3 it is #[no_mangle] static SERIAL_JTAG_FIFO_REG: usize = 0x60043000)
- SERIAL_JTAG_CONF_REG (e.g. on ESP32-C3 it is #[no_mangle] static SERIAL_JTAG_CONF_REG: usize = 0x60043004).