add consts

asm/eval.c

@@ -85,6 +85,9 @@ EvaledOperand eval_operand_to_imm(
                 case IdentResolTy_Label:
                 case IdentResolTy_SubLabel:
                     return (EvaledOperand) { .ty = EoTy_Imm, .imm = re->ip };
+                case IdentResolTy_Const:
+                    return (EvaledOperand) { .ty = EoTy_Imm, .imm = re->value };
+                    break;
             }
             fprintf(stderr, "unreachable\n");
             exit(1);

asm/main.c

@@ -1,3 +1,4 @@
+#include "asm/report.h"
 #include "assemble.h"
 #include "eval.h"
 #include "parse.h"
@@ -91,6 +92,15 @@ int main(int argc, char** argv)
         .text_len = parser.lexer.text_len,
     };
 
+    IdentResolver resolver;
+    ident_resolver_construct(&resolver);
+
+    OperandEvaluator evaluator = {
+        .re = &resolver,
+        .rep = &rep,
+        .second_pass = false,
+    };
+
     size_t lines_capacity = 1024;
     PLine** lines = malloc(sizeof(PLine*) * lines_capacity);
     size_t lines_size = 0;
@@ -100,24 +110,47 @@ int main(int argc, char** argv)
             lines_capacity += 2;
             lines = realloc(lines, sizeof(PLine*) * lines_capacity);
         }
-        PLine* line = parser_next(&parser);
+        PStmt* stmt = parser_next_stmt(&parser);
-        if (!line) {
+        if (!stmt) {
             continue;
         }
-        lines[lines_size++] = line;
+        switch (stmt->ty) {
+            case PStmtTy_Line:
+                lines[lines_size++] = stmt->line;
+                // NOTE: Shallow free.
+                free(stmt);
+                break;
+            case PStmtTy_Global:
+                pstmt_free(stmt);
+                break;
+            case PStmtTy_Extern:
+                pstmt_free(stmt);
+                break;
+            case PStmtTy_Const: {
+                const IdentResol* existing
+                    = ident_resolver_resolve(&resolver, stmt->ident);
+                if (existing != NULL) {
+                    REPORTF_ERROR("redefinition of constant '%s'", stmt->ident);
+                    reporter_print_loc(&rep, stmt->loc);
+                    pstmt_free(stmt);
+                    continue;
+                }
+                EvaledOperand evaled
+                    = eval_operand_to_imm(&evaluator, stmt->value);
+                if (evaled.ty == EoTy_Err) {
+                    pstmt_free(stmt);
+                    continue;
+                }
+                ident_resolver_define_const(
+                    &resolver, asm_strdup(stmt->ident), stmt->loc, evaled.imm);
+                pstmt_free(stmt);
+                break;
+            }
+        }
     }
 
     errors_occured &= parser_error_occured(&parser);
 
-    IdentResolver resolver;
-    ident_resolver_construct(&resolver);
-
-    OperandEvaluator evaluator = {
-        .re = &resolver,
-        .rep = &rep,
-        .second_pass = false,
-    };
-
     size_t chunk_capacity = 64;
     uint16_t* chunk = malloc(sizeof(uint16_t) * chunk_capacity);
 

asm/parse.c

@@ -126,6 +126,26 @@ void pline_free(PLine* pline)
     free(pline);
 }
 
+PStmt* pstmt_new_line(Loc loc, PLine* line)
+{
+    PStmt* stmt = malloc(sizeof(PStmt));
+    *stmt = (PStmt) { .ty = PStmtTy_Line, .loc = loc, .line = line };
+    return stmt;
+}
+
+PStmt* pstmt_new_ident(PStmtTy ty, Loc loc, char* ident)
+{
+    PStmt* stmt = malloc(sizeof(PStmt));
+    *stmt = (PStmt) { .ty = ty, .loc = loc, .ident = ident, .value = NULL };
+    return stmt;
+}
+PStmt* pstmt_new_const(PStmtTy ty, Loc loc, char* ident, POperand* value)
+{
+    PStmt* stmt = malloc(sizeof(PStmt));
+    *stmt = (PStmt) { .ty = ty, .loc = loc, .ident = ident, .value = value };
+    return stmt;
+}
+
 void pstmt_free(PStmt* stmt)
 {
     switch (stmt->ty) {
@@ -134,9 +154,12 @@ void pstmt_free(PStmt* stmt)
             break;
         case PStmtTy_Global:
         case PStmtTy_Extern:
-        case PStmtTy_Define:
             free(stmt->ident);
             break;
+        case PStmtTy_Const:
+            free(stmt->ident);
+            poperand_free(stmt->value);
+            break;
     }
     free(stmt);
 }
@@ -184,7 +207,7 @@ static inline bool parser_eat(Parser* parser, TokTy ty)
     return false;
 }
 
-static inline char* parser_ident_val(const Parser* parser, Tok tok)
+static inline char* parser_text_val(const Parser* parser, Tok tok)
 {
     return asm_strndup(&parser->lexer.text[tok.loc.idx], tok.len);
 }
@@ -218,7 +241,7 @@ static inline PLabel* parser_parse_labels(
                 plabel_free(labels);
                 return NULL;
             }
-            char* label_ident = parser_ident_val(parser, parser->eaten);
+            char* label_ident = parser_text_val(parser, parser->eaten);
             if (!parser_eat(parser, ':')) {
                 parser_report(parser, "expected ':'", parser->tok.loc);
                 plabel_free(labels);
@@ -227,7 +250,7 @@ static inline PLabel* parser_parse_labels(
             }
             labels = plabel_new(labels, label_ident, true, loc);
         } else if (parser_eat(parser, TT_Ident)) {
-            *ident = parser_ident_val(parser, parser->eaten);
+            *ident = parser_text_val(parser, parser->eaten);
             *ident_loc = loc;
             if (!parser_eat(parser, ':')) {
                 break;
@@ -269,7 +292,7 @@ static inline POperand* parser_parse_operand_0(Parser* parser)
 {
     Loc loc = parser->tok.loc;
     if (parser_eat(parser, TT_Ident)) {
-        char* ident = parser_ident_val(parser, parser->eaten);
+        char* ident = parser_text_val(parser, parser->eaten);
         const char* reg_key[10] = {
             "r0", "r1", "r2", "r3", "r4", "rbp", "rsp", "rfl", "rcs", "rip"
         };
@@ -282,7 +305,7 @@ static inline POperand* parser_parse_operand_0(Parser* parser)
         }
         return poperand_new_str(PoTy_Ident, ident, parser->eaten.len, loc);
     } else if (parser_eat(parser, TT_Int)) {
-        char* str = parser_ident_val(parser, parser->eaten);
+        char* str = parser_text_val(parser, parser->eaten);
         uint64_t val = strtoull(str, NULL, 10);
         free(str);
         if (val > 0xffff) {
@@ -294,7 +317,7 @@ static inline POperand* parser_parse_operand_0(Parser* parser)
         uint16_t imm = (uint16_t)val;
         return poperand_new_imm(imm, loc);
     } else if (parser_eat(parser, TT_Binary)) {
-        char* str = parser_ident_val(parser, parser->eaten);
+        char* str = parser_text_val(parser, parser->eaten);
         uint64_t val = strtoull(&str[2], NULL, 2);
         free(str);
         if (val > 0xffff) {
@@ -306,7 +329,7 @@ static inline POperand* parser_parse_operand_0(Parser* parser)
         uint16_t imm = (uint16_t)val;
         return poperand_new_imm(imm, loc);
     } else if (parser_eat(parser, TT_Hex)) {
-        char* str = parser_ident_val(parser, parser->eaten);
+        char* str = parser_text_val(parser, parser->eaten);
         uint64_t val = strtoull(&str[2], NULL, 16);
         free(str);
         if (val > 0xffff) {
@@ -318,12 +341,12 @@ static inline POperand* parser_parse_operand_0(Parser* parser)
         uint16_t imm = (uint16_t)val;
         return poperand_new_imm(imm, loc);
     } else if (parser_eat(parser, TT_Char)) {
-        char* str = parser_ident_val(parser, parser->eaten);
+        char* str = parser_text_val(parser, parser->eaten);
         uint16_t imm = (uint16_t)literal_char_val(&str[1]);
         free(str);
         return poperand_new_imm(imm, loc);
     } else if (parser_eat(parser, TT_Str)) {
-        char* lit = parser_ident_val(parser, parser->eaten);
+        char* lit = parser_text_val(parser, parser->eaten);
         size_t lit_len = strlen(lit);
         char* str = calloc(lit_len - 1, sizeof(char));
         size_t str_len = 0;
@@ -337,7 +360,7 @@ static inline POperand* parser_parse_operand_0(Parser* parser)
             parser_report(parser, "expected identifier", parser->tok.loc);
             return NULL;
         }
-        char* ident = parser_ident_val(parser, parser->eaten);
+        char* ident = parser_text_val(parser, parser->eaten);
         return poperand_new_str(PoTy_SubLabel, ident, parser->eaten.len, loc);
     } else if (parser_eat(parser, '(')) {
         POperand* operand = parser_parse_operand_2(parser, parser_binary_prec);
@@ -431,7 +454,7 @@ static inline POperand* parser_parse_operand_3(Parser* parser)
     if (!parser_test(parser, TT_Ident)) {
         return parser_parse_operand_2(parser, parser_binary_prec);
     }
-    char* ident = parser_ident_val(parser, parser->tok);
+    char* ident = parser_text_val(parser, parser->tok);
     if (strcmp(ident, "u8") == 0) {
         free(ident);
         parser_step(parser);
@@ -473,15 +496,14 @@ static inline void parser_skip_to_next_line(Parser* parser)
     }
 }
 
-PLine* parser_next(Parser* parser)
+PLine* parser_next_line(Parser* parser)
 {
     char* ident;
     Loc loc;
     PLabel* labels = parser_parse_labels(parser, &ident, &loc);
 
     const size_t max_ops_size = 64;
-    // TODO: Move allocation out-of-band.
+    POperand* ops[64];
-    POperand** ops = malloc(sizeof(POperand) * max_ops_size);
     size_t ops_size = 0;
 
     if (!parser_test(parser, TT_Eof) && !parser_test(parser, '\n')) {
@@ -520,15 +542,77 @@ PLine* parser_next(Parser* parser)
     parser_skip_newlines(parser);
 
     PLine* line = pline_new(ident, labels, loc, ops_size, ops);
-    free(ops);
     return line;
 
 error_free_ops:
     for (size_t i = 0; i < ops_size; ++i)
         if (ops[i])
             poperand_free(ops[i]);
-    free(ops);
     plabel_free(labels);
     free(ident);
     return NULL;
 }
+
+static inline PStmtTy pstmt_keyword_ty(const char* ident)
+{
+    const PStmtTy tys[] = {
+        PStmtTy_Global,
+        PStmtTy_Extern,
+        PStmtTy_Const,
+    };
+    const char* keywords[] = {
+        "global",
+        "extern",
+        "const",
+    };
+    static_assert(
+        sizeof(keywords) / sizeof(keywords[0]) == sizeof(tys) / sizeof(tys[0]),
+        "mismatch");
+
+    size_t amount = sizeof(tys) / sizeof(tys[0]);
+    for (size_t i = 0; i < amount; ++i) {
+        if (strcmp(ident, keywords[i]) == 0) {
+            return tys[i];
+        }
+    }
+    return PStmtTy_Line;
+}
+
+PStmt* parser_next_stmt(Parser* parser)
+{
+    parser_skip_newlines(parser);
+    Loc loc = parser->tok.loc;
+    if (!parser_test(parser, TT_Ident)) {
+        PLine* line = parser_next_line(parser);
+        if (!line)
+            return NULL;
+        return pstmt_new_line(loc, line);
+    }
+    char* keyword = parser_text_val(parser, parser->tok);
+    PStmtTy ty = pstmt_keyword_ty(keyword);
+    free(keyword);
+    switch (ty) {
+        case PStmtTy_Global:
+        case PStmtTy_Extern:
+        case PStmtTy_Const: {
+            parser_step(parser);
+            if (!parser_eat(parser, TT_Ident)) {
+                parser_report(parser, "expected identifier", parser->tok.loc);
+                return NULL;
+            }
+            char* ident = parser_text_val(parser, parser->eaten);
+            if (ty != PStmtTy_Const) {
+                return pstmt_new_ident(ty, loc, ident);
+            }
+            POperand* value = parser_parse_operand_3(parser);
+            return pstmt_new_const(ty, loc, ident, value);
+            break;
+        }
+        default:
+            break;
+    }
+    PLine* line = parser_next_line(parser);
+    if (!line)
+        return NULL;
+    return pstmt_new_line(loc, line);
+}

asm/parse.h

@@ -84,17 +84,24 @@ typedef enum {
     PStmtTy_Line,
     PStmtTy_Global,
     PStmtTy_Extern,
-    PStmtTy_Define,
+    PStmtTy_Const,
 } PStmtTy;
 
 typedef struct {
     PStmtTy ty;
+    Loc loc;
     union {
         PLine* line;
-        char* ident;
+        struct {
+            char* ident;
+            POperand* value;
+        };
     };
 } PStmt;
 
+PStmt* pstmt_new_line(Loc loc, PLine* line);
+PStmt* pstmt_new_ident(PStmtTy ty, Loc loc, char* ident);
+PStmt* pstmt_new_const(PStmtTy ty, Loc loc, char* ident, POperand* value);
 void pstmt_free(PStmt* stmt);
 
 typedef struct {
@@ -107,4 +114,5 @@ typedef struct {
 void parser_construct(Parser* parser, const char* filename, const char* text);
 bool parser_done(const Parser* parser);
 bool parser_error_occured(const Parser* parser);
-PLine* parser_next(Parser* parser);
+PLine* parser_next_line(Parser* parser);
+PStmt* parser_next_stmt(Parser* parser);

asm/resolve.c

@@ -9,6 +9,7 @@ void ident_resol_destroy(IdentResol* resol)
             break;
         case IdentResolTy_Label:
         case IdentResolTy_SubLabel:
+        case IdentResolTy_Const:
             free(resol->ident);
             break;
     }
@@ -77,6 +78,18 @@ void ident_resolver_define_sublabel(
     };
 }
 
+void ident_resolver_define_const(
+    IdentResolver* resolver, char* ident, Loc loc, uint16_t value)
+{
+    size_t i = ident_resolver_first_empty(resolver);
+    resolver->resols[i] = (IdentResol) {
+        .ident = ident,
+        .loc = loc,
+        .ty = IdentResolTy_Const,
+        .value = value,
+    };
+}
+
 const IdentResol* ident_resolver_resolve(
     const IdentResolver* resolver, const char* ident)
 {

asm/resolve.h

@@ -7,6 +7,7 @@ typedef enum {
     IdentResolTy_None,
     IdentResolTy_Label,
     IdentResolTy_SubLabel,
+    IdentResolTy_Const,
 } IdentResolTy;
 
 typedef struct IdentResol IdentResol;
@@ -17,6 +18,7 @@ struct IdentResol {
     IdentResolTy ty;
     union {
         uint16_t ip;
+        uint16_t value;
     };
 };
 
@@ -36,5 +38,7 @@ void ident_resolver_define_label(
     IdentResolver* resolver, char* ident, Loc loc, uint16_t asm_ip);
 void ident_resolver_define_sublabel(
     IdentResolver* resolver, char* ident, Loc loc, uint16_t asm_ip);
+void ident_resolver_define_const(
+    IdentResolver* resolver, char* ident, Loc loc, uint16_t value);
 const IdentResol* ident_resolver_resolve(
     const IdentResolver* resolver, const char* ident);

kern/main.asm

@@ -1,17 +1,41 @@
 
+const Fl_Zero 0
+const Fl_Eq 1
+const Fl_Be 2
+const Fl_Lt 3
+const Fl_Err 4
+const Fl_Int 5
+const Fl_Vcd 6
+
+const Int_DiskRead 0
+const Int_DiskWrite 1
+const Int_Key 32
+
+const Device_Keyboard 0
+
+const vcd_ch_width 8
+const vcd_ch_height 8
+const vcd_width_in_ch 40
+const vcd_height_in_ch 12
+
+const vcd_px_width 4
+const vcd_px_height 8
+const vcd_width_in_px vcd_width_in_ch * vcd_ch_width * vcd_px_width
+const vcd_height_in_px vcd_height_in_ch * vcd_ch_height * vcd_px_height
+
 start:
     ; rsp points *at* the top element
     mov rbp, 2048
     mov rsp, 2048 - 2
 
     lit interrupt_table
-    or rfl, rfl, 1 << 5 ; Fl_Int
+    or rfl, rfl, 1 << Fl_Int
 
-    or rfl, rfl, 1 << 6 ; Fl_Vcd
+    or rfl, rfl, 1 << Fl_Vcd
 
     mov r0, 512
     mov r1, 1
-    int 0 ; Int_DiskRead
+    int Int_DiskRead
 
 main_loop:
     hlt
@@ -24,7 +48,7 @@ interrupt_table:
     nop
 
 keyboard_interrupt:
-    and rfl, rfl, !(1 << 5) ; Fl_Int
+    and rfl, rfl, !(1 << Fl_Int)
     push rbp
     mov rbp, rsp
     push r0
@@ -32,21 +56,21 @@ keyboard_interrupt:
     push r2
     push r3
 
-    in r0, 0 ; Device_Keyboard
+    in r0, Device_Keyboard
 
     cmp r0, 44
     mov r1, rfl
-    and r1, r1, 1 << 1 ; Fl_Eq
+    and r1, r1, 1 << Fl_Eq
     jnz r1, .L0
 
     cmp r0, 42
     mov r1, rfl
-    and r1, r1, 1 << 1 ; Fl_Eq
+    and r1, r1, 1 << Fl_Eq
     jnz r1, .L1
 
     cmp r0, 40
     mov r1, rfl
-    and r1, r1, 1 << 1 ; Fl_Eq
+    and r1, r1, 1 << Fl_Eq
     jnz r1, .L2
 
     jmp .L3
@@ -60,7 +84,7 @@ keyboard_interrupt:
     mov r1, u16 [screen_x]
     cmp r1, 0
     mov r2, rfl
-    and r2, r2, 1 << 1 ; Fl_Eq
+    and r2, r2, 1 << Fl_Eq
     jnz r2, .L4
     sub r1, r1, 1
     mov u16 [screen_x], r1
@@ -92,7 +116,7 @@ keyboard_interrupt:
     pop r0
     mov rsp, rbp
     pop rbp
-    or rfl, rfl, 1 << 5 ; Fl_Int
+    or rfl, rfl, 1 << Fl_Int
     iret
 
 put_char:
@@ -102,7 +126,7 @@ put_char:
     push r2
 
     mov r2, u16 [screen_y]
-    mul r2, r2, 40 ; vcd_width_in_ch
+    mul r2, r2, vcd_width_in_ch
     mov r1, u16 [screen_x]
     add r1, r1, 0x0c00
     add r1, r1, r2
@@ -112,9 +136,9 @@ put_char:
     add r1, r1, 1
     mov u16 [screen_x], r1
 
-    cmp r1, 40 ; vcd_width_in_ch
+    cmp r1, vcd_width_in_ch
     mov r2, rfl
-    and r2, r2, 1 << 1 ; Fl_Eq
+    and r2, r2, 1 << Fl_Eq
     jnz r2, .L0
     jmp .L1