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@drtrigon
Created Mar 20, 2019
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#include <stdint.h>
#define NULL 0
//#define LED (*(volatile uint32_t*)0x02000000)
#define LED (*(volatile uint32_t*)0x03000000)
#define reg_uart_clkdiv (*(volatile uint32_t*)0x02000004)
#define reg_uart_data (*(volatile uint32_t*)0x02000008)
//#define F_CPU 25000000 // Hz
#define F_CPU 12000000 // Hz
#define BAUD_RATE 115200 // bit/s
int getchar_available()
{
return reg_uart_data & 0x100;
}
char getchar()
{
return reg_uart_data & 0xFF;
}
void putchar(char c)
{
if (c == '\n')
putchar('\r');
reg_uart_data = c;
}
void main(void)
{
int c, cnt, pos, val, len;
char *cp;
void *base_addr = NULL;
reg_uart_clkdiv = F_CPU/BAUD_RATE; // sets baudrate (115200 @ 25 MHz)
/* Appease gcc's uninitialized variable warnings */
val = 0;
cp = NULL; /* shut up uninitialized use warnings */
prompt:
pos = 0;
c = 0x76720A0D; /* "\r\nrv" */
do {
putchar(c);
c >>= 8;
if (c == 0 && pos == 0) {
pos = -1;
c = 0x203E3233; /* "32> " */
}
} while (c != 0);
next:
pos = -1;
len = 255;
cnt = 2;
loop:
/* Blink LEDs while waiting for serial input */
do {
#if 0
if (pos < 0) {
// RDTSC(val);
val++;
if (val & 0x08000000)
c = 0xff;
else
c = 0;
if ((val & 0xff) > ((val >> 19) & 0xff))
LED = c ^ 0x0f;
else
LED = c ^ 0xf0;
} else
LED = (int) cp >> 8;
#endif
c = reg_uart_data;
} while ( (c & 0x100) == 0);
// c = getchar();
c &= 0xFF;
LED = c;
if (pos < 0) {
if (c == 'S')
pos = 0;
else {
if (c == '\r') /* CR ? */
goto prompt;
/* Echo char */
if (c >= 32)
putchar(c);
}
val = 0;
goto loop;
}
if (c >= 10 && c <= 13) /* CR / LF ? */
goto next;
val <<= 4;
if (c >= 'a')
c -= 32;
if (c >= 'A')
val |= c - 'A' + 10;
else
val |= c - '0';
pos++;
/* Address width */
if (pos == 1) {
if (val >= 7 && val <= 9)
{
__asm __volatile__(
// "li s0, 0x00008000;" /* 32K RAM top = stack address */
// "li s0, 0x00002000;" /* 8K RAM top = stack address */
"li s0, 0x00000400;" /* 1K RAM top = stack address */
"mv ra, zero;"
"jr %0;"
:
: "r" (base_addr)
);
}
if (val <= 3)
len = (val << 1) + 5;
val = 0;
goto loop;
}
/* Byte count */
if (pos == 3) {
cnt += (val << 1);
val = 0;
goto loop;
}
/* Valid len? */
if (len < 6)
goto loop;
/* End of address */
if (pos == len) {
cp = (char *) val;
if (base_addr == NULL)
base_addr = (void *) val;
goto loop;
}
if (pos > len && (pos & 1) && pos < cnt)
*cp++ = val;
goto loop;
/* Unreached */
}
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