--- /dev/null
+// Misc utility functions.
+//
+// Copyright (C) 2008,2009 Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU LGPLv3 license.
+
+#include "util.h" // call16
+#include "bregs.h" // struct bregs
+#include "config.h" // BUILD_STACK_ADDR
+
+
+/****************************************************************
+ * 16bit calls
+ ****************************************************************/
+
+// Call a function with a specified register state. Note that on
+// return, the interrupt enable/disable flag may be altered.
+inline void
+call16(struct bregs *callregs)
+{
+ if (!MODESEGMENT && getesp() > BUILD_STACK_ADDR)
+ panic("call16 with invalid stack\n");
+ asm volatile(
+#if MODE16 == 1
+ "calll __call16\n"
+ "cli\n"
+ "cld"
+#else
+ "calll __call16_from32"
+#endif
+ : "+a" (callregs), "+m" (*callregs)
+ :
+ : "ebx", "ecx", "edx", "esi", "edi", "cc", "memory");
+}
+
+inline void
+call16big(struct bregs *callregs)
+{
+ ASSERT32FLAT();
+ if (getesp() > BUILD_STACK_ADDR)
+ panic("call16 with invalid stack\n");
+ asm volatile(
+ "calll __call16big_from32"
+ : "+a" (callregs), "+m" (*callregs)
+ :
+ : "ebx", "ecx", "edx", "esi", "edi", "cc", "memory");
+}
+
+inline void
+__call16_int(struct bregs *callregs, u16 offset)
+{
+ if (MODESEGMENT)
+ callregs->code.seg = GET_SEG(CS);
+ else
+ callregs->code.seg = SEG_BIOS;
+ callregs->code.offset = offset;
+ call16(callregs);
+}
+
+
+/****************************************************************
+ * String ops
+ ****************************************************************/
+
+// Sum the bytes in the specified area.
+u8
+checksum_far(u16 buf_seg, void *buf_far, u32 len)
+{
+ SET_SEG(ES, buf_seg);
+ u32 i;
+ u8 sum = 0;
+ for (i=0; i<len; i++)
+ sum += GET_VAR(ES, ((u8*)buf_far)[i]);
+ return sum;
+}
+
+u8
+checksum(void *buf, u32 len)
+{
+ return checksum_far(GET_SEG(SS), buf, len);
+}
+
+size_t
+strlen(const char *s)
+{
+ if (__builtin_constant_p(s))
+ return __builtin_strlen(s);
+ const char *p = s;
+ while (*p)
+ p++;
+ return p-s;
+}
+
+// Compare two areas of memory.
+int
+memcmp(const void *s1, const void *s2, size_t n)
+{
+ while (n) {
+ if (*(u8*)s1 != *(u8*)s2)
+ return *(u8*)s1 < *(u8*)s2 ? -1 : 1;
+ s1++;
+ s2++;
+ n--;
+ }
+ return 0;
+}
+
+// Compare two strings.
+int
+strcmp(const char *s1, const char *s2)
+{
+ for (;;) {
+ if (*s1 != *s2)
+ return *s1 < *s2 ? -1 : 1;
+ if (! *s1)
+ return 0;
+ s1++;
+ s2++;
+ }
+}
+
+inline void
+memset_far(u16 d_seg, void *d_far, u8 c, size_t len)
+{
+ SET_SEG(ES, d_seg);
+ asm volatile(
+ "rep stosb %%es:(%%di)"
+ : "+c"(len), "+D"(d_far)
+ : "a"(c)
+ : "cc", "memory");
+}
+
+inline void
+memset16_far(u16 d_seg, void *d_far, u16 c, size_t len)
+{
+ len /= 2;
+ SET_SEG(ES, d_seg);
+ asm volatile(
+ "rep stosw %%es:(%%di)"
+ : "+c"(len), "+D"(d_far)
+ : "a"(c)
+ : "cc", "memory");
+}
+
+void *
+memset(void *s, int c, size_t n)
+{
+ while (n)
+ ((char *)s)[--n] = c;
+ return s;
+}
+
+void memset_fl(void *ptr, u8 val, size_t size)
+{
+ if (MODESEGMENT)
+ memset_far(FLATPTR_TO_SEG(ptr), (void*)(FLATPTR_TO_OFFSET(ptr)),
+ val, size);
+ else
+ memset(ptr, val, size);
+}
+
+inline void
+memcpy_far(u16 d_seg, void *d_far, u16 s_seg, const void *s_far, size_t len)
+{
+ SET_SEG(ES, d_seg);
+ u16 bkup_ds;
+ asm volatile(
+ "movw %%ds, %w0\n"
+ "movw %w4, %%ds\n"
+ "rep movsb (%%si),%%es:(%%di)\n"
+ "movw %w0, %%ds"
+ : "=&r"(bkup_ds), "+c"(len), "+S"(s_far), "+D"(d_far)
+ : "r"(s_seg)
+ : "cc", "memory");
+}
+
+inline void
+memcpy_fl(void *d_fl, const void *s_fl, size_t len)
+{
+ if (MODESEGMENT)
+ memcpy_far(FLATPTR_TO_SEG(d_fl), (void*)FLATPTR_TO_OFFSET(d_fl)
+ , FLATPTR_TO_SEG(s_fl), (void*)FLATPTR_TO_OFFSET(s_fl)
+ , len);
+ else
+ memcpy(d_fl, s_fl, len);
+}
+
+void *
+#undef memcpy
+memcpy(void *d1, const void *s1, size_t len)
+#if MODESEGMENT == 0
+#define memcpy __builtin_memcpy
+#endif
+{
+ SET_SEG(ES, GET_SEG(SS));
+ void *d = d1;
+ if (((u32)d1 | (u32)s1 | len) & 3) {
+ // non-aligned memcpy
+ asm volatile(
+ "rep movsb (%%esi),%%es:(%%edi)"
+ : "+c"(len), "+S"(s1), "+D"(d)
+ : : "cc", "memory");
+ return d1;
+ }
+ // Common case - use 4-byte copy
+ len /= 4;
+ asm volatile(
+ "rep movsl (%%esi),%%es:(%%edi)"
+ : "+c"(len), "+S"(s1), "+D"(d)
+ : : "cc", "memory");
+ return d1;
+}
+
+// Copy to/from memory mapped IO. IO mem is very slow, so yield
+// periodically.
+void
+iomemcpy(void *d, const void *s, u32 len)
+{
+ yield();
+ while (len > 3) {
+ u32 copylen = len;
+ if (copylen > 2048)
+ copylen = 2048;
+ copylen /= 4;
+ len -= copylen * 4;
+ asm volatile(
+ "rep movsl (%%esi),%%es:(%%edi)"
+ : "+c"(copylen), "+S"(s), "+D"(d)
+ : : "cc", "memory");
+ yield();
+ }
+ if (len)
+ // Copy any remaining bytes.
+ memcpy(d, s, len);
+}
+
+void *
+memmove(void *d, const void *s, size_t len)
+{
+ if (s >= d)
+ return memcpy(d, s, len);
+
+ d += len-1;
+ s += len-1;
+ while (len--) {
+ *(char*)d = *(char*)s;
+ d--;
+ s--;
+ }
+
+ return d;
+}
+
+// Copy a string - truncating it if necessary.
+char *
+strtcpy(char *dest, const char *src, size_t len)
+{
+ char *d = dest;
+ while (--len && *src != '\0')
+ *d++ = *src++;
+ *d = '\0';
+ return dest;
+}
+
+// locate first occurance of character c in the string s
+char *
+strchr(const char *s, int c)
+{
+ for (; *s; s++)
+ if (*s == c)
+ return (char*)s;
+ return NULL;
+}
+
+// Remove any trailing blank characters (spaces, new lines, carriage returns)
+void
+nullTrailingSpace(char *buf)
+{
+ int len = strlen(buf);
+ char *end = &buf[len-1];
+ while (end >= buf && *end <= ' ')
+ *(end--) = '\0';
+}
+
+/****************************************************************
+ * Keyboard calls
+ ****************************************************************/
+
+// See if a keystroke is pending in the keyboard buffer.
+static int
+check_for_keystroke(void)
+{
+ struct bregs br;
+ memset(&br, 0, sizeof(br));
+ br.flags = F_IF;
+ br.ah = 1;
+ call16_int(0x16, &br);
+ return !(br.flags & F_ZF);
+}
+
+// Return a keystroke - waiting forever if necessary.
+static int
+get_raw_keystroke(void)
+{
+ struct bregs br;
+ memset(&br, 0, sizeof(br));
+ br.flags = F_IF;
+ call16_int(0x16, &br);
+ return br.ah;
+}
+
+// Read a keystroke - waiting up to 'msec' milliseconds.
+int
+get_keystroke(int msec)
+{
+ u32 end = calc_future_timer(msec);
+ for (;;) {
+ if (check_for_keystroke())
+ return get_raw_keystroke();
+ if (check_timer(end))
+ return -1;
+ wait_irq();
+ }
+}
