initial commit

oscar64/samples/memmap/tsr.c

@@ -0,0 +1,70 @@
+#include <string.h>
+#include <stdio.h>
+#include <c64/asm6502.h>
+
+// Invoke resident section with "SYS 49152" from basic
+
+// not much space, so we go with a smaller stack size
+
+#pragma stacksize(256)
+
+// shrink size of startup section
+
+#pragma section(startup, 0);
+#pragma region(startup, 0x0801, 0x0870, , , { startup } )
+
+// section for code copy
+
+#pragma section(rcode, 0)
+#pragma region(rcode, 0x0870, 0x0900, , , { rcode } )
+
+// main section to stay resident, save three bytes at the
+// beginning to have space for an entry jump
+
+#pragma region(main, 0x0903, 0x1900, , , {code, data, bss, heap, stack}, 0xc003 )
+
+// resident entry routine
+
+void tsr(void)
+{
+	// Initialize stack pointer
+
+	__asm {
+		lda #$ff
+		sta __sp
+		lda	#$cf
+		sta	__sp +1
+	}
+
+	// do something useless
+
+	printf(p"Hello World\n");
+
+	// and done
+}
+	
+// Now the copy code section
+
+#pragma code(rcode)
+
+int main(void)
+{
+	// source and target address to copy, no memcpy as it is itself
+	// not yet copied
+
+	char * dp = (char *)0xc000;
+	char * sp = (char *)0x0903;
+
+	// A jmp to the code at the absolute address 0xc000 / 49152
+
+	dp += asm_ab(dp, ASM_JMP, (unsigned)tsr);
+
+	// then the code 
+
+	for(unsigned i=0; i<0xffd; i++)
+		*dp++ = *sp++;
+
+	// now we are done
+
+	return 0;
+}