dreamcast/runtime.cpp
Zack Buhman d912278afd serial_transfer: self-relocate to the end of system memory
The serial_transfer loader, as long as the target program voluntarily
terminates itself at some point, is able to load multiple programs
consecutively without requiring a physical power cycle to reload the
transfer program from CD.

The current example.mk juggles between two different "memory layouts",
one for "burn to a physical CD" and another for "load via serial
cable". Because the serial_transfer program now relocates itself to
the end of system memory, this means the 0x8c010000 area is now usable
by programs that are loaded by serial_transfer.
2024-03-13 20:56:37 +08:00

77 lines
1.9 KiB
C++

#include <cstdint>
#include <type_traits>
#include "sh7091/cache.hpp"
#include "string.hpp"
extern uint32_t __text_link_start __asm("__text_link_start");
extern uint32_t __text_link_end __asm("__text_link_end");
extern uint32_t __text_load_start __asm("__text_load_start");
extern uint32_t __data_link_start __asm("__data_link_start");
extern uint32_t __data_link_end __asm("__data_link_end");
extern uint32_t __data_load_start __asm("__data_load_start");
extern uint32_t __rodata_link_start __asm("__rodata_link_start");
extern uint32_t __rodata_link_end __asm("__rodata_link_end");
extern uint32_t __rodata_load_start __asm("__rodata_load_start");
extern uint32_t __ctors_link_start __asm("__ctors_link_start");
extern uint32_t __ctors_link_end __asm("__ctors_link_end");
extern uint32_t __bss_link_start __asm("__bss_link_start");
extern uint32_t __bss_link_end __asm("__bss_link_end");
extern void main();
typedef void(init_t)(void);
extern "C"
void runtime_init()
__attribute__((section(".text.startup.runtime_init")));
void copy(uint32_t * start, const uint32_t * end, uint32_t * load)
__attribute__((section(".text.startup.copy")));
void copy(uint32_t * start, const uint32_t * end, uint32_t * load)
{
if (start != load) {
while (start < end) {
*start++ = *load++;
}
}
}
extern "C"
void runtime_init()
{
// relocate text (if necessary)
copy(&__text_link_start, &__text_link_end, &__text_load_start);
// relocate data (if necessary)
copy(&__data_link_start, &__data_link_end, &__data_load_start);
// relocate rodata (if necessary)
copy(&__rodata_link_start, &__rodata_link_end, &__rodata_load_start);
uint32_t * start;
uint32_t * end;
// clear BSS
start = &__bss_link_start;
end = &__bss_link_end;
while (start < end) {
*start++ = 0;
}
// call ctors
start = &__ctors_link_start;
end = &__ctors_link_end;
while (start < end) {
((init_t*)(*start++))();
}
cache::init();
}