begin implementing some helpers

--HG--
extra : convert_revision : svn%3A39bc706e-5318-0410-9160-8a85361fbb7c/trunk%4042

sourcepawn/vm/msvc8/vm.vcproj

@@ -41,13 +41,13 @@
 				Name="VCCLCompilerTool"
 				Optimization="0"
 				AdditionalIncludeDirectories="..\..\include"
-				PreprocessorDefinitions="WIN32;_DEBUG;_CONSOLE"
+				PreprocessorDefinitions="WIN32;_DEBUG;_CONSOLE;_CRT_SECURE_NO_DEPRECATE"
 				MinimalRebuild="true"
 				BasicRuntimeChecks="3"
 				RuntimeLibrary="3"
 				UsePrecompiledHeader="0"
 				WarningLevel="3"
-				Detect64BitPortabilityProblems="true"
+				Detect64BitPortabilityProblems="false"
 				DebugInformationFormat="4"
 			/>
 			<Tool
@@ -176,7 +176,7 @@
 			UniqueIdentifier="{4FC737F1-C7A5-4376-A066-2A32D752A2FF}"
 			>
 			<File
-				RelativePath="..\test.c"
+				RelativePath="..\sp_vm.c"
 				>
 			</File>
 		</Filter>

sourcepawn/vm/sp_vm.c

@@ -0,0 +1,107 @@
+#include <limits.h>
+#include <assert.h>
+#include "sp_vm.h"
+
+#define CELLBOUNDMAX	(INT_MAX/sizeof(cell_t))
+#define STACKMARGIN		((cell_t)(16*sizeof(cell_t)))
+
+int main()
+{
+	/** temporary testing area */
+	sp_context_t ctx;
+	cell_t l, *p;
+
+	ctx.data = (uint8_t *)malloc(50000);
+	ctx.memory = 50000;
+	ctx.heapbase = 200;
+	ctx.hp = ctx.heapbase;
+	ctx.sp = 45000;
+
+	assert(SP_HeapAlloc(&ctx, 500, &l, &p) == SP_ERR_NONE);
+	assert(SP_HeapPop(&ctx, l) == SP_ERR_NONE);
+	assert(SP_HeapRelease(&ctx, l) == SP_ERR_NONE);
+	assert(SP_HeapRelease(&ctx, 4) == SP_ERR_INVALID_ADDRESS);
+	assert(SP_HeapAlloc(&ctx, 500, &l, &p) == SP_ERR_NONE);
+	assert(SP_HeapRelease(&ctx, l) == SP_ERR_NONE);
+
+	return 0;
+}
+
+int SP_HeapAlloc(sp_context_t *ctx, unsigned int cells, cell_t *local_addr, cell_t **phys_addr)
+{
+	cell_t *addr;
+	ucell_t realmem;
+
+#if 0
+	if (cells > CELLBOUNDMAX)
+	{
+		return SP_ERR_PARAM;
+	}
+#else
+	assert(cells < CELLBOUNDMAX);
+#endif
+
+	realmem = cells * sizeof(cell_t);
+
+	/**
+	 * Check if the space between the heap and stack is sufficient.
+	 */
+	if ((cell_t)(ctx->sp - ctx->hp - realmem) < STACKMARGIN)
+	{
+		return SP_ERR_HEAPLOW;
+	}
+
+	addr = (cell_t *)(ctx->data + ctx->hp);
+	/* store size of allocation in cells */
+	*addr = (cell_t)cells;
+	addr++;
+	ctx->hp += sizeof(cell_t);
+
+	*local_addr = ctx->hp;
+
+	if (phys_addr)
+	{
+		*phys_addr = addr;
+	}
+
+	ctx->hp += realmem;
+
+	return SP_ERR_NONE;
+}
+
+int SP_HeapPop(sp_context_t *ctx, cell_t local_addr)
+{
+	cell_t cellcount;
+	cell_t *addr;
+
+	/* check the bounds of this address */
+	local_addr -= sizeof(cell_t);
+	if (local_addr < ctx->heapbase || local_addr >= ctx->sp)
+	{
+		return SP_ERR_INVALID_ADDRESS;
+	}
+
+	addr = (cell_t *)(ctx->data + local_addr);
+	cellcount = (*addr) * sizeof(cell_t);
+	/* check if this memory count looks valid */
+	if (ctx->hp - cellcount - sizeof(cell_t) != local_addr)
+	{
+		return SP_ERR_INVALID_ADDRESS;
+	}
+
+	ctx->hp = local_addr;
+
+	return SP_ERR_NONE;
+}
+
+int SP_HeapRelease(sp_context_t *ctx, cell_t local_addr)
+{
+	if (local_addr < ctx->heapbase)
+	{
+		return SP_ERR_INVALID_ADDRESS;
+	}
+
+	ctx->hp = local_addr - sizeof(cell_t);
+
+	return SP_ERR_NONE;
+}