Diff: vm/mem.c

Revision:

0:65f1469d6bfb

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/vm/mem.c	Sat Mar 02 11:54:20 2013 +0000
@@ -0,0 +1,147 @@
+/*
+# This file is Copyright 2002 Dean Hall.
+# This file is part of the PyMite VM.
+# This file is licensed under the MIT License.
+# See the LICENSE file for details.
+*/
+
+
+#undef __FILE_ID__
+#define __FILE_ID__ 0x0D
+
+
+/**
+ * \file
+ * \brief VM Memory
+ *
+ * VM memory operations.
+ * Implementations and stubs for getByte and memCopy functions.
+ * Functions to load object images from static memory.
+ */
+
+
+#include "pm.h"
+
+
+uint16_t
+mem_getWord(PmMemSpace_t memspace, uint8_t const **paddr)
+{
+    /* PyMite is little endian; get low byte first */
+    uint8_t blo = mem_getByte(memspace, paddr);
+    uint8_t bhi = mem_getByte(memspace, paddr);
+
+    return (uint16_t)(blo | (bhi << (int8_t)8));
+}
+
+
+uint32_t
+mem_getInt(PmMemSpace_t memspace, uint8_t const **paddr)
+{
+    /* PyMite is little endian; get low word first */
+    uint16_t wlo = mem_getWord(memspace, paddr);
+    uint32_t whi = mem_getWord(memspace, paddr);
+
+    return (uint32_t)(wlo | (whi << (int8_t)16));
+}
+
+
+#ifdef HAVE_FLOAT
+float
+mem_getFloat(PmMemSpace_t memspace, uint8_t const **paddr)
+{
+    union
+    {
+        char c[4];
+        float f;
+    }
+    v;
+
+#ifdef PM_FLOAT_BIG_ENDIAN
+    /* If the architecture is Big Endian, reverse the bytes of the float */
+    v.c[3] = mem_getByte(memspace, paddr);
+    v.c[2] = mem_getByte(memspace, paddr);
+    v.c[1] = mem_getByte(memspace, paddr);
+    v.c[0] = mem_getByte(memspace, paddr);
+
+#else
+    v.c[0] = mem_getByte(memspace, paddr);
+    v.c[1] = mem_getByte(memspace, paddr);
+    v.c[2] = mem_getByte(memspace, paddr);
+    v.c[3] = mem_getByte(memspace, paddr);
+
+#ifndef PM_FLOAT_LITTLE_ENDIAN
+#warning Neither PM_FLOAT_LITTLE_ENDIAN nor PM_FLOAT_BIG_ENDIAN is defined \
+         for this platform; defaulting to little endian.
+#endif
+#endif
+
+    return v.f;
+}
+#endif /* HAVE_FLOAT */
+
+
+void
+mem_copy(PmMemSpace_t memspace,
+         uint8_t **pdest, uint8_t const **psrc, uint16_t count)
+{
+    /* Copy memory from RAM */
+    if (memspace == MEMSPACE_RAM)
+    {
+        sli_memcpy(*pdest, *psrc, count);
+        *psrc += count;
+        *pdest += count;
+        return;
+    }
+
+    /* Copy memory from non-RAM to RAM */
+    else
+    {
+        uint8_t b;
+
+        for (; count > 0; count--)
+        {
+            b = mem_getByte(memspace, psrc);
+            **pdest = b;
+            (*pdest)++;
+        }
+        return;
+    }
+}
+
+
+uint16_t
+mem_getStringLength(PmMemSpace_t memspace, uint8_t const *const pstr)
+{
+    uint8_t const *psrc;
+
+    /* If source is in RAM, use a possibly optimized strlen */
+    if (memspace == MEMSPACE_RAM)
+    {
+        return sli_strlen((char const *)pstr);
+    }
+
+    /* Otherwise calculate string length */
+    psrc = pstr;
+    while (mem_getByte(memspace, &psrc) != (uint8_t)0);
+    return psrc - pstr - 1;
+}
+
+
+PmReturn_t
+mem_cmpn(uint8_t *cname, uint16_t cnamelen, PmMemSpace_t memspace,
+         uint8_t const **paddr)
+{
+    uint16_t i;
+    uint8_t b;
+
+    /* Iterate over all characters */
+    for (i = 0; i < cnamelen; i++)
+    {
+        b = mem_getByte(memspace, paddr);
+        if (cname[i] != b)
+        {
+            return PM_RET_NO;
+        }
+    }
+    return PM_RET_OK;
+}