From 7418a5042471a3a7f05283d36e45b6b422d9785b Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Mon, 1 Nov 2021 14:30:30 +0100
Subject: Add x86_64 compilation for arithmetic expressions

---
 src/compiler.h | 115 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 115 insertions(+)
 create mode 100644 src/compiler.h

(limited to 'src/compiler.h')

diff --git a/src/compiler.h b/src/compiler.h
new file mode 100644
index 0000000..3fed075
--- /dev/null
+++ b/src/compiler.h
@@ -0,0 +1,115 @@
+#ifndef BDL_COMPILER_H
+#define BDL_COMPILER_H
+
+
+#define PRELUDE_FILE "src/x86_64/prelude.asm"
+#define POSTLUDE_FILE "src/x86_64/postlude.asm"
+
+void compile_object(Object *obj);
+void compile_fixnum(Object *obj);
+void compile_proc_call(Object *obj);
+void compile(Root *roots);
+
+void
+emit_file(char *file_name) {
+    FILE *file = fopen(file_name, "r");
+    if (!file) {
+        fprintf(stderr, "error: couldn't open input file: %s\n", file_name);
+        exit(EXIT_FAILURE);
+    }
+    char buf[1024];
+    size_t n = 0;
+    while ((n = fread(&buf, 1, 1024, file)) > 0) {
+        fwrite(buf, 1, n, stdout);
+    }
+}
+
+void
+compile_fixnum(Object *obj) {
+    printf("    ;; -- compile_fixnum --\n");
+    printf("    mov     rax, %ld\n", obj->fixnum);
+    printf("    push    rax\n");
+    printf("    ;; --------------------\n");
+}
+
+typedef enum OpType {
+    OP_ADD,
+    OP_SUB,
+    OP_MUL,
+    OP_DIV,
+    OP_MOD,
+} OpType;
+
+void
+arithmetic_op(OpType type) {
+    printf("    ;; -- arithmetic_op --\n");
+    printf("    pop     rcx\n");
+    printf("    pop     rax\n");
+    switch (type) {
+        case OP_ADD: {
+            printf("    add     rax, rcx\n");
+        } break;
+        case OP_SUB: {
+            printf("    sub     rax, rcx\n");
+        } break;
+        case OP_MUL: {
+            printf("    mul     rcx\n");
+        } break;
+        case OP_DIV: {
+            printf("    mov     rdx, 0\n");
+            printf("    div     rcx\n");
+        } break;
+        case OP_MOD: {
+            printf("    mov     rdx, 0\n");
+            printf("    div     rcx\n");
+            printf("    mov     rax, rdx\n");
+        } break;
+    }
+    printf("    push    rax\n");
+    printf("    ;; -------------------\n");
+}
+
+void
+compile_proc_call(Object *obj) {
+    printf("    ;; -- compile_proc_call --\n");
+    OpType op;
+    if (sv_equal(&obj->head->text, &STRING("+"))) { op = OP_ADD;}
+    if (sv_equal(&obj->head->text, &STRING("-"))) { op = OP_SUB;}
+    if (sv_equal(&obj->head->text, &STRING("*"))) { op = OP_MUL;}
+    if (sv_equal(&obj->head->text, &STRING("/"))) { op = OP_DIV;}
+    if (sv_equal(&obj->head->text, &STRING("%"))) { op = OP_MOD;}
+    // TODO: Resolve function call.
+    Object *args = obj->tail;
+    // TODO: capture first operand in the accumulator. Number of arguments
+    // checking should have been handled in the parser.
+    compile_object(args->head);
+    args = args->tail;
+    while (args != NULL) {
+        compile_object(args->head);
+        args = args->tail;
+        arithmetic_op(op);
+    }
+    printf("    ;; -----------------------\n");
+}
+
+void
+compile_object(Object *obj) {
+    switch (obj->type) {
+        case OBJ_TYPE_FIXNUM: { compile_fixnum(obj); } break;
+        case OBJ_TYPE_PAIR: { compile_proc_call(obj); } break;
+        default: break;
+    }
+}
+
+void
+compile(Root *roots) {
+    emit_file(PRELUDE_FILE);
+    for (size_t i = 0; i < array_size(roots); i++) {
+        Object *root = roots[i];
+        compile_object(root);
+        // OBJ_PRINT(root);
+    }
+    emit_file(POSTLUDE_FILE);
+}
+
+#endif // BDL_COMPILER_H
-- 
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