Starting on asm, implementing extern function call so progress is visible

1 files changed, 383 insertions, 0 deletions

diff --git a/src/asm/x86_64.c b/src/asm/x86_64.c
new file mode 100644
index 0000000..2cbeead
--- /dev/null
+++ b/src/asm/x86_64.c
@@ -0,0 +1,383 @@
+#include "../../include/asm/x86_64.h"
+
+#include "../../include/std/mem.h"
+#include "../../include/std/log.h"
+#include <errno.h>
+#include <assert.h>
+#include <stdio.h>
+
+#include <sys/mman.h>
+
+#define REX_W 0x48
+
+void asm_ptr_init(AsmPtr *self, Reg64 base) {
+    self->base = base;
+    self->index = -1;
+    self->disp = 0;
+    self->scale = 0;
+}
+
+void asm_ptr_init_index(AsmPtr *self, Reg64 base, Reg64 index) {
+    self->base = base;
+    self->index = index;
+    self->disp = 0;
+    self->scale = 0;
+}
+
+void asm_ptr_init_disp(AsmPtr *self, Reg64 base, i32 disp) {
+    self->base = base;
+    self->index = -1;
+    self->disp = disp;
+    self->scale = 0;
+}
+
+void asm_ptr_init_index_disp(AsmPtr *self, Reg64 base, Reg64 index, i32 disp) {
+    self->base = base;
+    self->index = index;
+    self->disp = disp;
+    self->scale = 0;
+}
+
+int asm_init(Asm *self) {
+    self->size = am_pagesize();
+    amal_log_debug("asm: page size: %u", self->size);
+    self->code = mmap(NULL, self->size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+    if(self->code == MAP_FAILED)
+        return -errno;
+    self->code_it = self->code;
+    return 0;
+}
+
+void asm_deinit(Asm *self) {
+    if(self->code)
+        munmap(self->code, self->size);
+    self->code = NULL;
+    self->code_it = NULL;
+    self->size = 0;
+}
+
+static void asm_print_code_hex(Asm *self) {
+    u8 *ptr;
+    int off;
+    ptr = self->code;
+    off = 0;
+    while(ptr != self->code_it) {
+        printf("%02x", *ptr);
+        ++ptr;
+        ++off;
+        if(off == 8) {
+            putc('\n', stdout);
+            off = 0;
+        } else {
+            putc(' ', stdout);
+        }
+    }
+    if(off != 0)
+        putc('\n', stdout);
+}
+
+int asm_execute(Asm *self) {
+    void (*func)();
+    if(mprotect(self->code, self->size, PROT_READ | PROT_EXEC) != 0)
+        return -errno;
+
+    asm_print_code_hex(self);
+
+    /* TODO: Verify if this is valid on all platforms. According to ISO C standard it isn't? */
+    *(void**)(&func) = self->code;
+    func();
+    return 0;
+}
+
+/* TODO: See how this can be optimized */
+static CHECK_RESULT int asm_ensure_capacity(Asm *self, usize size) {
+    usize current_offset;
+    current_offset = (u8*)self->code_it - (u8*)self->code;
+    if(current_offset + size > self->size) {
+        void *new_mem;
+        usize new_size;
+        new_size = self->size + am_pagesize();
+        new_mem = mmap(NULL, new_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+        if(self->code == MAP_FAILED)
+            return -errno;
+
+        am_memcpy(new_mem, self->code, self->size);
+        self->code = new_mem;
+        self->size = new_size;
+        self->code_it = (u8*)self->code + current_offset;
+    }
+    return 0;
+}
+
+static isize asm_get_capacity_left(Asm *self) {
+    return (isize)self->size - (isize)((u8*)self->code_it - (u8*)self->code);
+}
+
+int asm_nop(Asm *self) {
+    return_if_error(asm_ensure_capacity(self, 1));
+    *self->code_it++ = 0x90;
+    return 0;
+}
+
+static i32 abs_i32(i32 value) {
+    return value >= 0 ? value : -value;
+}
+
+/*
+TODO: Implement 1 and 2 byte displacement?
+There has to be at least 6 bytes left in the asm buffer before calling this function.
+*/
+static void asm_rm(Asm *self, AsmPtr *mem, Reg64 reg) {
+    u8 rm_byte;
+    u8 disp_bytes;
+    assert(asm_get_capacity_left(self) >= 6);
+    if((int)mem->index != -1) {
+        u8 sib_offset;
+        if(mem->disp == 0) {
+            rm_byte = 0x04;
+            disp_bytes = 0;
+        } else if(abs_i32(mem->disp) <= INT8_MAX) {
+            rm_byte = 0x44;
+            disp_bytes = 1;
+        } else {
+            rm_byte = 0x84;
+            disp_bytes = 4;
+        }
+
+        #ifdef DEBUG
+        if(mem->scale != 0 && mem->scale != 2 && mem->scale != 4 && mem->scale != 8) {
+            amal_log_error("Invalid scale %d, expected 0, 2, 4, or 8", mem->scale);
+            assert(bool_false);
+        }
+        #endif
+        assert(mem->base != RBP && "TODO: Implement RBP base for sib byte. RBP is special and requires different logic");
+        sib_offset = (mem->scale << 5) + 8*mem->index + mem->base;
+
+        *self->code_it++ = rm_byte;
+        *self->code_it++ = sib_offset;
+    } else {
+        if(mem->disp == 0) {
+            if(mem->base == RBP) {
+                rm_byte = 0x45;
+                disp_bytes = 1;
+            } else {
+                rm_byte = mem->base;
+                disp_bytes = 0;
+            }
+        } else if(abs_i32(mem->disp) <= INT8_MAX) {
+            rm_byte = 0x40 + mem->base;
+            disp_bytes = 1;
+        } else {
+            rm_byte = 0x80 + mem->base;
+            disp_bytes = 4;
+        }
+        *self->code_it++ = (reg << 3) | rm_byte;
+    }
+
+    am_memcpy(self->code_it, &mem->disp, disp_bytes);
+    self->code_it += disp_bytes;
+}
+
+/* There has to be at least 1 byte left in the asm buffer before calling this function. */
+static void asm_rr(Asm *self, Reg64 dst, Reg64 src) {
+    assert(asm_get_capacity_left(self) >= 1);
+    *self->code_it++ = 0xC0 + dst + 8*src;
+}
+
+/* TODO: Implement 1 and 2 byte immediate? */
+int asm_mov_mi(Asm *self, AsmPtr *dst, i32 immediate) {
+    /* 12 bytes is the maximum size of the instruction. We don't how how large it will be so we prepare for the largest size */
+    return_if_error(asm_ensure_capacity(self, 12));
+    *self->code_it++ = REX_W;
+    *self->code_it++ = 0xC7;
+    asm_rm(self, dst, 0);
+    am_memcpy(self->code_it, &immediate, sizeof(immediate));
+    self->code_it += sizeof(immediate);
+    return 0;
+}
+
+int asm_mov_mr(Asm *self, AsmPtr *dst, Reg64 src) {
+    /* 8 bytes is the maximum size of the instruction. We don't how how large it will be so we prepare for the largest size */
+    return_if_error(asm_ensure_capacity(self, 8));
+    *self->code_it++ = REX_W;
+    *self->code_it++ = 0x89;
+    asm_rm(self, dst, src);
+    return 0;
+}
+
+int asm_mov_rm(Asm *self, Reg64 dst, AsmPtr *src) {
+    /* 8 bytes is the maximum size of the instruction. We don't how how large it will be so we prepare for the largest size */
+    return_if_error(asm_ensure_capacity(self, 8));
+    *self->code_it++ = REX_W;
+    *self->code_it++ = 0x8B;
+    asm_rm(self, src, dst);
+    return 0;
+}
+
+int asm_mov_ri(Asm *self, Reg64 dst, i64 immediate) {
+    /* 10 bytes is the maximum size of the instruction. We don't how how large it will be so we prepare for the largest size */
+    return_if_error(asm_ensure_capacity(self, 10));
+    *self->code_it++ = REX_W;
+    *self->code_it++ = 0xB8 + dst;
+    am_memcpy(self->code_it, &immediate, sizeof(immediate));
+    self->code_it += sizeof(immediate);
+    return 0;
+}
+
+int asm_mov_rr(Asm *self, Reg64 dst, Reg64 src) {
+    /* 3 bytes is the maximum size of the instruction. We don't how how large it will be so we prepare for the largest size */
+    return_if_error(asm_ensure_capacity(self, 3));
+    *self->code_it++ = REX_W;
+    *self->code_it++ = 0x89;
+    asm_rr(self, dst, src);
+    return 0;
+}
+
+int asm_add_rr(Asm *self, Reg64 dst, Reg64 src) {
+    /* 3 bytes is the maximum size of the instruction. We don't how how large it will be so we prepare for the largest size */
+    return_if_error(asm_ensure_capacity(self, 3));
+    *self->code_it++ = REX_W;
+    *self->code_it++ = 0x01;
+    asm_rr(self, dst, src);
+    return 0;
+}
+
+int asm_sub_rr(Asm *self, Reg64 dst, Reg64 src) {
+    /* 3 bytes is the maximum size of the instruction. We don't how how large it will be so we prepare for the largest size */
+    return_if_error(asm_ensure_capacity(self, 3));
+    *self->code_it++ = REX_W;
+    *self->code_it++ = 0x29;
+    asm_rr(self, dst, src);
+    return 0;
+}
+
+int asm_imul_rr(Asm *self, Reg64 dst, Reg64 src) {
+    /* 3 bytes is the maximum size of the instruction. We don't how how large it will be so we prepare for the largest size */
+    return_if_error(asm_ensure_capacity(self, 4));
+    *self->code_it++ = REX_W;
+    *self->code_it++ = 0x0F;
+    *self->code_it++ = 0xAF;
+    asm_rr(self, dst, src);
+    return 0;
+}
+
+int asm_pushr(Asm *self, Reg64 reg) {
+    return_if_error(asm_ensure_capacity(self, 1));
+    *self->code_it++ = 0x50 + reg;
+    return 0;
+}
+
+int asm_popr(Asm *self, Reg64 reg) {
+    return_if_error(asm_ensure_capacity(self, 1));
+    *self->code_it++ = 0x58 + reg;
+    return 0;
+}
+
+/* /r */
+#define DEFINE_INS_RM(mnemonic, opcode)                         \
+int asm_##mnemonic##_rm32(Asm *self, Reg32 dst, Reg32 src) {    \
+    return_if_error(asm_ensure_capacity(self, 2));              \
+    *self->code_it++ = opcode;                             \
+    *self->code_it++ = 0xC0 + 8*dst + src;                 \
+    return 0;                                                   \
+}                                                               \
+                                                                \
+int asm_##mnemonic##_rm64(Asm *self, Reg64 dst, Reg64 src) {    \
+    return_if_error(asm_ensure_capacity(self, 1));              \
+    *self->code_it++ = REX_W;                               \
+    return asm_##mnemonic##_rm32(self, (Reg32)dst, (Reg32)src); \
+}
+
+DEFINE_INS_RM(mov, 0x8B)
+DEFINE_INS_RM(add, 0x03)
+DEFINE_INS_RM(sub, 0x2B)
+DEFINE_INS_RM(and, 0x23)
+DEFINE_INS_RM(or, 0x0B)
+DEFINE_INS_RM(xor, 0x33)
+DEFINE_INS_RM(cmp, 0x3B)
+
+/*
+    /number
+    The number is called the extension, a number from 0 to 7;
+    It's a number used to extend the opcode type, since the instruction only uses
+    one register the other register can be encoded for that.
+*/
+#define DEFINE_INS_EXT_IMM(mnemonic, extension)                      \
+int asm_##mnemonic##_rm32_imm(Asm *self, Reg32 reg, i32 immediate) { \
+    if(abs_i32(immediate) <= INT8_MAX) {                                 \
+        return_if_error(asm_ensure_capacity(self, 3));               \
+        *self->code_it++ = 0x83;                                \
+        *self->code_it++ = 0xC0 + 8*extension + reg;            \
+        *self->code_it++ = (u8)immediate;                       \
+    } else {                                                         \
+        return_if_error(asm_ensure_capacity(self, 6));               \
+        *self->code_it++ = 0x81;                                \
+        *self->code_it++ = 0xC0 + 8*extension + reg;            \
+        am_memcpy(self->code_it, &immediate, sizeof(immediate));     \
+        self->code_it += sizeof(immediate);                          \
+    }                                                                \
+    return 0;                                                        \
+}                                                                    \
+                                                                     \
+int asm_##mnemonic##_rm64_imm(Asm *self, Reg64 reg, i32 immediate) { \
+    return_if_error(asm_ensure_capacity(self, 1));                   \
+    *self->code_it++ = REX_W;                                    \
+    return asm_##mnemonic##_rm32_imm(self, (Reg32)reg, immediate);   \
+}
+
+DEFINE_INS_EXT_IMM(add, 0)
+DEFINE_INS_EXT_IMM(or, 1)
+DEFINE_INS_EXT_IMM(adc, 2)
+DEFINE_INS_EXT_IMM(sbb, 3)
+DEFINE_INS_EXT_IMM(and, 4)
+DEFINE_INS_EXT_IMM(sub, 5)
+DEFINE_INS_EXT_IMM(xor, 6)
+DEFINE_INS_EXT_IMM(cmp, 7)
+
+/*
+    /number
+    The number is called the extension, a number from 0 to 7;
+    It's a number used to extend the opcode type, since the instruction only uses
+    one register the other register can be encoded for that.
+*/
+#define DEFINE_INS_SHIFT_IMM8(mnemonic, extension)                  \
+int asm_##mnemonic##_rm32_imm(Asm *self, Reg32 reg, i8 immediate) { \
+    if(immediate == 1) {                                            \
+        return_if_error(asm_ensure_capacity(self, 2));              \
+        *self->code_it++ = 0xC1;                               \
+        *self->code_it++ = 0xC0 + 8*reg + extension;           \
+    } else {                                                        \
+        return_if_error(asm_ensure_capacity(self, 3));              \
+        *self->code_it++ = 0xD1;                               \
+        *self->code_it++ = 0xC0 + 8*reg + extension;           \
+        *self->code_it++ = immediate;                          \
+    }                                                               \
+    return 0;                                                       \
+}                                                                   \
+                                                                    \
+int asm_##mnemonic##_rm64_imm(Asm *self, Reg64 reg, i8 immediate) { \
+    return_if_error(asm_ensure_capacity(self, 1));                  \
+    *self->code_it++ = REX_W;                                   \
+    return asm_##mnemonic##_rm32_imm(self, (Reg32)reg, immediate);  \
+}
+
+DEFINE_INS_SHIFT_IMM8(rol, 0)
+DEFINE_INS_SHIFT_IMM8(ror, 1)
+DEFINE_INS_SHIFT_IMM8(rcl, 2)
+DEFINE_INS_SHIFT_IMM8(rcr, 3)
+DEFINE_INS_SHIFT_IMM8(shl, 4)
+DEFINE_INS_SHIFT_IMM8(shr, 5)
+/*DEFINE_INS_SHIFT_IMM8(shl, 6)*/
+DEFINE_INS_SHIFT_IMM8(sar, 7)
+
+int asm_ret(Asm *self, u16 bytes) {
+    if(bytes == 0) {
+        return_if_error(asm_ensure_capacity(self, 1));
+        *self->code_it++ = 0xC3;
+    } else {
+        return_if_error(asm_ensure_capacity(self, 3));
+        *self->code_it++ = 0xC2;
+        am_memcpy(self->code_it, &bytes, sizeof(bytes));
+    }
+    return 0;
+}
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