1 files changed, 206 insertions, 0 deletions
diff --git a/software/shared/syscall.c b/software/shared/syscall.c
new file mode 100644
index 0000000..2e4199f
--- /dev/null
+++ b/software/shared/syscall.c
@@ -0,0 +1,206 @@
+// See LICENSE for license details.
+
+/* This is an incomplete version of a syscall library, 
+ * which really only supports simple reads and writes over UART.
+ */
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <stddef.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/stat.h>
+#include <sys/times.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "encoding.h"
+
+#include "shared.h"
+
+volatile uint64_t tohost __attribute__((aligned(64)));
+volatile uint64_t fromhost __attribute__((aligned(64)));
+
+void write_hex(int fd, uint32_t hex){
+  uint8_t ii;
+  uint8_t jj;
+  char towrite;
+  write( fd , "0x", 2 );
+  for (ii = 8 ; ii > 0; ii--){
+    jj = ii-1;
+    uint8_t digit = ((hex & (0xF << (jj*4))) >> (jj*4));
+    towrite = digit < 0xA ? ('0' + digit) : ('A' +  (digit - 0xA));
+    write( fd, &towrite, 1);
+  }
+
+}
+
+               
+void _exit(int code)
+{
+  volatile uint32_t* leds = (uint32_t*) (GPIO_BASE_ADDR + GPIO_OUT_OFFSET);
+  const char * message = "\nProgam has exited with code:";
+  
+  *leds = (~(code));
+
+  write(STDERR_FILENO, message, strlen(message));
+  write_hex(STDERR_FILENO, code);
+
+  while (1);
+    
+}
+
+void *sbrk(ptrdiff_t incr)
+{
+  //  extern char _end[];
+  //  extern char _heap_end[];
+  //  static char *curbrk = _end;
+
+  //  if ((curbrk + incr < _end) || (curbrk + incr > _heap_end))
+    return NULL - 1;
+
+    //  curbrk += incr;
+    //return curbrk - incr;
+}
+
+static int stub(int err)
+{
+  errno = err;
+  return -1;
+}
+
+int open(const char* name, int flags, int mode)
+{
+  return stub(ENOENT);
+}
+
+int openat(int dirfd, const char* name, int flags, int mode)
+{
+  return stub(ENOENT);
+}
+
+int close(int fd)
+{
+  return stub(EBADF);
+}
+
+int execve(const char* name, char* const argv[], char* const env[])
+{
+  return stub(ENOMEM);
+}
+
+int fork()
+{
+  return stub(EAGAIN);
+}
+
+int fstat(int fd, struct stat *st)
+{
+  if (isatty(fd)) {
+    st->st_mode = S_IFCHR;
+    return 0;
+  }
+
+  return stub(EBADF);
+}
+
+int getpid()
+{
+  return 1;
+}
+
+int isatty(int fd)
+{
+  if (fd == STDOUT_FILENO || fd == STDERR_FILENO)
+    return 1;
+
+  errno = EBADF;
+  return 0;
+}
+
+int kill(int pid, int sig)
+{
+  return stub(EINVAL);
+}
+
+int link(const char *old_name, const char *new_name)
+{
+  return stub(EMLINK);
+}
+
+off_t lseek(int fd, off_t ptr, int dir)
+{
+  if (isatty(fd))
+    return 0;
+
+  return stub(EBADF);
+}
+
+ssize_t read(int fd, void* ptr, size_t len)
+{
+  int i;
+  uint8_t * current = (uint8_t*) ptr;
+  volatile uint8_t  * uart_rx = (uint8_t*) (UART_BASE_ADDR + UART_RX_OFFSET);
+  volatile uint32_t * uart_rx_cnt = (uint32_t*) (UART_BASE_ADDR + UART_RX_COUNT_OFFSET);
+
+  ssize_t result = 0;
+  
+  if (isatty(fd)) {
+    
+    for (current = (uint8_t*) ptr;
+	 (current < ((uint8_t*) ptr) + len) && (*uart_rx_cnt > 0);
+	 current ++){
+      *current = *uart_rx;
+      result ++;
+    }
+    return result;
+
+  }
+ 
+  return stub(EBADF);
+}
+
+int stat(const char* file, struct stat* st)
+{
+  return stub(EACCES);
+}
+
+clock_t times(struct tms* buf)
+{
+  return stub(EACCES);
+}
+
+int unlink(const char* name)
+{
+  return stub(ENOENT);
+}
+
+int wait(int* status)
+{
+  return stub(ECHILD);
+}
+
+ssize_t write(int fd, const void* ptr, size_t len)
+{
+
+  const uint8_t * current = (const char*) ptr;
+  volatile uint32_t * uart_tx_count = (uint32_t*) (UART_BASE_ADDR + UART_TX_COUNT_OFFSET);
+  volatile uint8_t *  uart_tx = (uint8_t*) (UART_BASE_ADDR + UART_TX_OFFSET);
+
+  size_t jj;
+  if (isatty(fd)) {
+    
+    for (jj = 0; jj < len; jj++){
+
+      while ((*uart_tx_count) < 1);
+      *uart_tx = current[jj];
+
+      if (current[jj] == '\n'){
+	while ((*uart_tx_count) < 1);
+	*uart_tx = '\r';
+      }
+    }
+    return len;
+  } 
+  return stub(EBADF);
+}