hello_world_small_q72.c
/* * "Small Hello World" example. * * This example prints 'Hello from Nios II' to the STDOUT stream. It runs on * the Nios II 'standard', 'full_featured', 'fast', and 'low_cost' example * designs. It requires a STDOUT device in your system's hardware. * * The purpose of this example is to demonstrate the smallest possible Hello * World application, using the Nios II HAL library. The memory footprint * of this hosted application is ~332 bytes by default using the standard * reference design. For a more fully featured Hello World application * example, see the example titled "Hello World". * * The memory footprint of this example has been reduced by making the * following changes to the normal "Hello World" example. * Check in the Nios II Software Developers Manual for a more complete * description. * * In the SW Application project (small_hello_world): * * - In the C/C++ Build page * * - Set the Optimization Level to -Os * * In System Library project (small_hello_world_syslib): * - In the C/C++ Build page * * - Set the Optimization Level to -Os * * - Define the preprocessor option ALT_NO_INSTRUCTION_EMULATION * This removes software exception handling, which means that you cannot * run code compiled for Nios II cpu with a hardware multiplier on a core * without a the multiply unit. Check the Nios II Software Developers * Manual for more details. * * - In the System Library page: * - Set Periodic system timer and Timestamp timer to none * This prevents the automatic inclusion of the timer driver. * * - Set Max file descriptors to 4 * This reduces the size of the file handle pool. * * - Check Main function does not exit * - Uncheck Clean exit (flush buffers) * This removes the unneeded call to exit when main returns, since it * won't. * * - Check Don't use C++ * This builds without the C++ support code. * * - Check Small C library * This uses a reduced functionality C library, which lacks * support for buffering, file IO, floating point and getch(), etc. * Check the Nios II Software Developers Manual for a complete list. * * - Check Reduced device drivers * This uses reduced functionality drivers if they're available. For the * standard design this means you get polled UART and JTAG UART drivers, * no support for the LCD driver and you lose the ability to program * CFI compliant flash devices. * * - Check Access device drivers directly * This bypasses the device file system to access device drivers directly. * This eliminates the space required for the device file system services. * It also provides a HAL version of libc services that access the drivers * directly, further reducing space. Only a limited number of libc * functions are available in this configuration. * * - Use ALT versions of stdio routines: * * Function Description * =============== ===================================== * alt_printf Only supports %s, %x, and %c ( < 1 Kbyte) * alt_putstr Smaller overhead than puts with direct drivers * Note this function doesn't add a newline. * alt_putchar Smaller overhead than putchar with direct drivers * alt_getchar Smaller overhead than getchar with direct drivers * */ #include "sys/alt_stdio.h" int main() { alt_putstr("Hello from Nios II!\n"); /* Event loop never exits. */ while (1); return 0; }
Maintained by John Loomis, updated Wed Jan 16 15:54:12 2008