From 0c81ee06d19d1d7f67dab3c2c9da268b0c55e3c0 Mon Sep 17 00:00:00 2001
From: Jacob McDonnell <jacob@jacobmcdonnell.com>
Date: Sat, 14 Mar 2026 18:44:18 -0400
Subject: feat: Initial parsing of instructions

Initial ability to parse basic instructions. Currently hex numbers are
broken and immediates with labels (movl $str, %ecx) are broken.
---
 src/parser.y | 101 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 101 insertions(+)
 create mode 100644 src/parser.y

(limited to 'src/parser.y')

diff --git a/src/parser.y b/src/parser.y
new file mode 100644
index 0000000..719643d
--- /dev/null
+++ b/src/parser.y
@@ -0,0 +1,101 @@
+%{
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <getopt.h>
+
+size_t line_number = 1;
+
+extern int yylex();
+extern int yyparse();
+extern FILE *yyin;
+void yyerror(const char *s);
+%}
+
+%union {
+    int i_val;
+    float f_val;
+    char *s_val;
+    char *symbol;
+}
+
+%token <i_val> T_INTEGER
+%token <f_val> T_FLOAT
+%token <s_val> T_STRING
+%token <symbol> T_LABEL
+%token <symbol> T_INSTRUCTION
+%token T_ENDL
+%token T_COMMA
+%token T_IMMEDIATE
+%%
+asm:
+    statements
+    ;
+
+statements:
+    statements statement
+    | statement
+    ;
+
+statement:
+    instruction_one_param_symbol T_ENDL
+    | instruction_one_param_immediate T_ENDL
+    | instruction_two_param_symbols T_ENDL
+    | instruction_symbol_immediate T_ENDL
+    | instruction_immediate_symbol T_ENDL
+    | T_ENDL
+    ;
+
+instruction_one_param_symbol:
+    T_INSTRUCTION T_LABEL {
+        printf("Found instruction %s(%s)\n", $1, $2);
+    };
+
+instruction_one_param_immediate:
+    T_INSTRUCTION T_IMMEDIATE T_INTEGER {
+        printf("Found instruction %s(%d)\n", $1, $3);
+    };
+instruction_two_param_symbols:
+    T_INSTRUCTION T_LABEL T_COMMA T_LABEL {
+        printf("Found instruction %s(%s, %s)\n", $1, $2, $4);
+    };
+
+instruction_symbol_immediate:
+    T_INSTRUCTION T_LABEL T_COMMA T_IMMEDIATE T_INTEGER {
+        printf("Found instruction %s(%s, %d)\n", $1, $2, $5);
+    }
+
+instruction_immediate_symbol:
+    T_INSTRUCTION T_IMMEDIATE T_INTEGER T_COMMA T_LABEL {
+        printf("Found instruction %s(%d, %s)\n", $1, $3, $5);
+    }
+%%
+
+void yyerror(const char *s) {
+    printf("Parser Error: %lu: %s\n", line_number, s);
+}
+
+int main(int argc, char *argv[]) {
+    FILE *input = stdin;
+
+    int j = 0;
+    while (j != -1) {
+        j = getopt(argc, argv, "o:");
+
+        switch (j) {
+        case 'o':
+            input = fopen(optarg, "r");
+            if (input == NULL) {
+                perror(argv[0]);
+                return -1;
+            }
+            break;
+        default:
+            break;
+        }
+    }
+
+    yyin = input;
+    yyparse();
+}
+
-- 
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