diff options
| -rw-r--r-- | .gitignore | 1 | ||||
| -rw-r--r-- | build.bat | 6 | ||||
| -rw-r--r-- | emulator/main.c (renamed from main.c) | 157 | ||||
| -rw-r--r-- | main.asm | 9 |
4 files changed, 172 insertions, 1 deletions
@@ -1 +1,2 @@ *.exe
+*.bin
@@ -1,2 +1,6 @@ -clang main.c -o riscv.exe -std=c11
+clang emulator/main.c -o emulator.exe -std=c11 -D_CRT_SECURE_NO_WARNINGS
+REM clang linker/main.c -o linker.exe -std=c11 -D_CRT_SECURE_NO_WARNINGS
+
+clang --target=riscv32 -march=rv32i -e _main -nostdlib main.asm -o main.bin
+
@@ -3,6 +3,134 @@ #include <inttypes.h>
#include <assert.h>
#include <stdbool.h>
+#include <string.h>
+
+#define ET_NONE 0x00
+#define ET_REL 0x01
+#define ET_EXEC 0x02
+#define ET_DYN 0x03
+#define ET_CORE 0x04
+
+struct Elf32Header
+{
+ uint8_t ident[16];
+ uint16_t type;
+ uint16_t machine;
+ uint32_t version;
+ uint32_t entry;
+ uint32_t phoff;
+ uint32_t shoff;
+ uint32_t flags;
+ uint16_t ehsize;
+ uint16_t phentsize;
+ uint16_t phnum;
+ uint16_t shentsize;
+ uint16_t shnum;
+ uint16_t shstrndx;
+};
+
+#define PT_NULL 0x00000000
+#define PT_LOAD 0x00000001
+#define PT_DYNAMIC 0x00000002
+#define PT_INTERP 0x00000003
+#define PT_NOTE 0x00000004
+#define PT_SHLIB 0x00000005
+#define PT_PHDR 0x00000006
+#define PT_TLS 0x00000007
+
+#define PF_X 0x1
+#define PF_W 0x2
+#define PF_R 0x4
+
+struct Elf32ProgramHeader
+{
+ uint32_t type;
+ uint32_t offset;
+ uint32_t vaddr;
+ uint32_t paddr;
+ uint32_t filesz;
+ uint32_t memsz;
+ uint32_t flags;
+ uint32_t align;
+};
+
+bool load_elf(const char* file, char* mem, uint32_t mem_size, uint32_t* start_address)
+{
+ FILE* fp = fopen(file, "rb");
+ if (fp == NULL)
+ {
+ printf("Couldn't open input file\n");
+ return false;
+ }
+
+ struct Elf32Header header;
+ size_t read = fread(&header, sizeof(struct Elf32Header), 1, fp);
+ if (read != 1)
+ {
+ printf("ELF header too small\n");
+ return false;
+ }
+
+ static uint8_t kValidIdent[7] = {
+ 0x7f, 0x45, 0x4c, 0x46,
+ 1, 1, 1
+ };
+ if (memcmp(kValidIdent, header.ident, 7) != 0)
+ {
+ printf("Invalid ELF header\n");
+ return false;
+ }
+
+ if (header.type != ET_EXEC)
+ {
+ printf("Can only link EXEC ELF files\n");
+ return false;
+ }
+
+ memset(mem, 0, mem_size);
+
+ assert(header.phnum == 0 || header.phentsize == sizeof(struct Elf32ProgramHeader));
+ for (uint32_t i = 0; i < header.phnum; ++i)
+ {
+ struct Elf32ProgramHeader pheader;
+
+ fseek(fp, header.phoff + i * header.phentsize, SEEK_SET);
+ read = fread(&pheader, sizeof(struct Elf32ProgramHeader), 1, fp);
+ if (read != 1)
+ {
+ printf("Error reading program header at index %u\n", i);
+ return false;
+ }
+
+ if (pheader.type == PT_LOAD)
+ {
+ if (pheader.paddr + pheader.memsz > mem_size)
+ {
+ printf("Memory not large enough for ELF file\n");
+ return false;
+ }
+
+ fseek(fp, pheader.offset, SEEK_SET);
+ read = fread(mem + pheader.paddr, pheader.filesz, 1, fp);
+ if (read != 1)
+ {
+ printf("Error when copying ELF segment\n");
+ return false;
+ }
+ }
+ }
+
+ if (header.entry > mem_size)
+ {
+ printf("Entry address out of bounds\n");
+ return false;
+ }
+
+ *start_address = header.entry;
+ fclose(fp);
+
+ return true;
+}
inline uint32_t sign_extend(uint32_t word, uint32_t size)
{
@@ -639,5 +767,34 @@ void test() int main(int argc, char* argv[])
{
test();
+
+ if (argc < 2)
+ {
+ printf("Usage: %s <input elf>\n", argv[0]);
+ return EXIT_FAILURE;
+ }
+
+ uint32_t mem_size = 16 * 1024 * 1024;
+ char* mem = (char*)malloc(mem_size);
+ uint32_t start_address = 0;
+
+ if (!load_elf(argv[1], mem, mem_size, &start_address))
+ {
+ printf("Error loading ELF into memory\n");
+ return EXIT_FAILURE;
+ }
+
+ struct Hart hart = {0};
+ hart.pc = start_address;
+
+ while (true)
+ {
+ uint32_t instruction = *(uint32_t*)(mem + hart.pc);
+ execute(&hart, instruction);
+ printf("pc=%x x1=%d x2=%d x3=%d x4=%d\n",
+ hart.pc, hart.regs[1], hart.regs[2], hart.regs[3], hart.regs[4]);
+ fgetc(stdout);
+ }
+
return EXIT_SUCCESS;
}
diff --git a/main.asm b/main.asm new file mode 100644 index 0000000..e90d6a2 --- /dev/null +++ b/main.asm @@ -0,0 +1,9 @@ +.section .text
+.global _main
+_main:
+ li x1, 5
+ addi x2, x1, 45
+
+loop:
+ addi x2, x2, 1
+ j loop
|