diff --git a/firmware/main.c b/firmware/main.c index 0eac52f..6c334ea 100644 --- a/firmware/main.c +++ b/firmware/main.c @@ -1,266 +1,24 @@ #include #include - -void *memcpy(void *restrict dest, const void *restrict src, size_t n) -{ - unsigned char *d = dest; - const unsigned char *s = src; - -#ifdef __GNUC__ - -#if __BYTE_ORDER == __LITTLE_ENDIAN -#define LS >> -#define RS << -#else -#define LS << -#define RS >> -#endif - - typedef uint32_t __attribute__((__may_alias__)) u32; - uint32_t w, x; - - for (; (uintptr_t)s % 4 && n; n--) *d++ = *s++; - - if ((uintptr_t)d % 4 == 0) { - for (; n>=16; s+=16, d+=16, n-=16) { - *(u32 *)(d+0) = *(u32 *)(s+0); - *(u32 *)(d+4) = *(u32 *)(s+4); - *(u32 *)(d+8) = *(u32 *)(s+8); - *(u32 *)(d+12) = *(u32 *)(s+12); - } - if (n&8) { - *(u32 *)(d+0) = *(u32 *)(s+0); - *(u32 *)(d+4) = *(u32 *)(s+4); - d += 8; s += 8; - } - if (n&4) { - *(u32 *)(d+0) = *(u32 *)(s+0); - d += 4; s += 4; - } - if (n&2) { - *d++ = *s++; *d++ = *s++; - } - if (n&1) { - *d = *s; - } - return dest; - } - - if (n >= 32) switch ((uintptr_t)d % 4) { - case 1: - w = *(u32 *)s; - *d++ = *s++; - *d++ = *s++; - *d++ = *s++; - n -= 3; - for (; n>=17; s+=16, d+=16, n-=16) { - x = *(u32 *)(s+1); - *(u32 *)(d+0) = (w LS 24) | (x RS 8); - w = *(u32 *)(s+5); - *(u32 *)(d+4) = (x LS 24) | (w RS 8); - x = *(u32 *)(s+9); - *(u32 *)(d+8) = (w LS 24) | (x RS 8); - w = *(u32 *)(s+13); - *(u32 *)(d+12) = (x LS 24) | (w RS 8); - } - break; - case 2: - w = *(u32 *)s; - *d++ = *s++; - *d++ = *s++; - n -= 2; - for (; n>=18; s+=16, d+=16, n-=16) { - x = *(u32 *)(s+2); - *(u32 *)(d+0) = (w LS 16) | (x RS 16); - w = *(u32 *)(s+6); - *(u32 *)(d+4) = (x LS 16) | (w RS 16); - x = *(u32 *)(s+10); - *(u32 *)(d+8) = (w LS 16) | (x RS 16); - w = *(u32 *)(s+14); - *(u32 *)(d+12) = (x LS 16) | (w RS 16); - } - break; - case 3: - w = *(u32 *)s; - *d++ = *s++; - n -= 1; - for (; n>=19; s+=16, d+=16, n-=16) { - x = *(u32 *)(s+3); - *(u32 *)(d+0) = (w LS 8) | (x RS 24); - w = *(u32 *)(s+7); - *(u32 *)(d+4) = (x LS 8) | (w RS 24); - x = *(u32 *)(s+11); - *(u32 *)(d+8) = (w LS 8) | (x RS 24); - w = *(u32 *)(s+15); - *(u32 *)(d+12) = (x LS 8) | (w RS 24); - } - break; - } - if (n&16) { - *d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++; - *d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++; - *d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++; - *d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++; - } - if (n&8) { - *d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++; - *d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++; - } - if (n&4) { - *d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++; - } - if (n&2) { - *d++ = *s++; *d++ = *s++; - } - if (n&1) { - *d = *s; - } - return dest; -#endif - - for (; n; n--) *d++ = *s++; - return dest; -} - -void *memset(void *dest, int c, size_t n) -{ - unsigned char *s = dest; - size_t k; - - /* Fill head and tail with minimal branching. Each - * conditional ensures that all the subsequently used - * offsets are well-defined and in the dest region. */ - - if (!n) return dest; - s[0] = c; - s[n-1] = c; - if (n <= 2) return dest; - s[1] = c; - s[2] = c; - s[n-2] = c; - s[n-3] = c; - if (n <= 6) return dest; - s[3] = c; - s[n-4] = c; - if (n <= 8) return dest; - - /* Advance pointer to align it at a 4-byte boundary, - * and truncate n to a multiple of 4. The previous code - * already took care of any head/tail that get cut off - * by the alignment. */ - - k = -(uintptr_t)s & 3; - s += k; - n -= k; - n &= -4; - -#ifdef __GNUC__ - typedef uint32_t __attribute__((__may_alias__)) u32; - typedef uint64_t __attribute__((__may_alias__)) u64; - - u32 c32 = ((u32)-1)/255 * (unsigned char)c; - - /* In preparation to copy 32 bytes at a time, aligned on - * an 8-byte bounary, fill head/tail up to 28 bytes each. - * As in the initial byte-based head/tail fill, each - * conditional below ensures that the subsequent offsets - * are valid (e.g. !(n<=24) implies n>=28). */ - - *(u32 *)(s+0) = c32; - *(u32 *)(s+n-4) = c32; - if (n <= 8) return dest; - *(u32 *)(s+4) = c32; - *(u32 *)(s+8) = c32; - *(u32 *)(s+n-12) = c32; - *(u32 *)(s+n-8) = c32; - if (n <= 24) return dest; - *(u32 *)(s+12) = c32; - *(u32 *)(s+16) = c32; - *(u32 *)(s+20) = c32; - *(u32 *)(s+24) = c32; - *(u32 *)(s+n-28) = c32; - *(u32 *)(s+n-24) = c32; - *(u32 *)(s+n-20) = c32; - *(u32 *)(s+n-16) = c32; - - /* Align to a multiple of 8 so we can fill 64 bits at a time, - * and avoid writing the same bytes twice as much as is - * practical without introducing additional branching. */ - - k = 24 + ((uintptr_t)s & 4); - s += k; - n -= k; - - /* If this loop is reached, 28 tail bytes have already been - * filled, so any remainder when n drops below 32 can be - * safely ignored. */ - - u64 c64 = c32 | ((u64)c32 << 32); - for (; n >= 32; n-=32, s+=32) { - *(u64 *)(s+0) = c64; - *(u64 *)(s+8) = c64; - *(u64 *)(s+16) = c64; - *(u64 *)(s+24) = c64; - } -#else - /* Pure C fallback with no aliasing violations. */ - for (; n; n--, s++) *s = c; -#endif - - return dest; -} - -#define reg_uart_data (*(volatile uint32_t*)0x300000) +#define reg_uart_data (*(volatile uint8_t*)0x3000000UL) void putchar(char c) { - if (c == '\n') - putchar('\r'); - reg_uart_data = c; + if (c == '\n') + putchar('\r'); + reg_uart_data = c; } void print(const char *p) { - while (*p) - putchar(*(p++)); + while (*p) + putchar(*(p++)); } -/* This is just for testing purposes and debugging - assembly code - */ -void test_func(void) -{ - int i = 42; - uint32_t test_array[100] = { [0 ... 99] = 0xDEADBEEF }; - - while(1) - { - i++; - test_array[0]++; - if(i==84) break; - } -} - - int main(void) { - int i = 0; - - test_func(); - - print("Hello World from a simple RV32I ISA emulator!\n"); - - while(1) - { - i++; + print("Hello World from a simple RV32I ISA emulator!\n"); - if(i==10) break; - } - - print("Bye!\n"); - - return 0; + return 0; } - - diff --git a/firmware/sections.lds b/firmware/sections.lds index 66071fc..cbaaa82 100644 --- a/firmware/sections.lds +++ b/firmware/sections.lds @@ -1,7 +1,7 @@ MEMORY { - FLASH (rx) : ORIGIN = 0x00100000, LENGTH = 0x004000 /* entire flash, 4 MiB */ - RAM (xrw) : ORIGIN = 0x00000000, LENGTH = 0x004000 /* 1 KB */ + FLASH (rx) : ORIGIN = 0x80000000, LENGTH = 0x001000 /* entire flash, 4 MiB */ + RAM (xrw) : ORIGIN = 0x80001000, LENGTH = 0x003000 /* 1 KB */ } SECTIONS { diff --git a/firmware/start.s b/firmware/start.s index c764f0a..40382ec 100644 --- a/firmware/start.s +++ b/firmware/start.s @@ -4,7 +4,7 @@ start: # zero-initialize register file addi x1, zero, 0 -li sp, 0x00001000 +li sp, 0x80004000 # x2 (sp) is initialized by reset addi x3, zero, 0 addi x4, zero, 0 @@ -37,7 +37,7 @@ addi x30, zero, 0 addi x31, zero, 0 # zero initialize entire scratchpad memory -li a0, 0x00000000 +li a0, 0x80001000 setmemloop: sw a0, 0(a0) addi a0, a0, 4