Add section directive.

3 files changed, 70 insertions, 3 deletions

diff --git a/asm.peg b/asm.peg
index 2251966..4b1828e 100644
--- a/asm.peg
+++ b/asm.peg
@@ -8,11 +8,11 @@ ws = [ \t]+
 eol = ws? "\n"
 
 stmt =
-    d:directive {$$ = d;}
+    '.' d:directive {$$ = d;}
   | i:instr { $$ = i; }
   | l:label {  $$ = l; } 
 
-directive = '.' (
+directive =
    "glob" 'o'? 'l' ws i:ident
    { $$.globl = (Globl){.kind = ASM_DIR_GLOBL, .name = i.ident.name }; }
   | "ascii" <'z'?> ws s:string
@@ -25,7 +25,23 @@ directive = '.' (
     { $$.balign = (Balign){.kind = ASM_DIR_BALIGN, .align = n.number.v }; }
   | "byte" ws n:number
     { $$.byte = (Byte){.kind = ASM_DIR_BYTE, .b = (uint8_t)n.number.v }; }
-)
+  | sd:section-directive { $$ = sd; }
+
+section-directive =
+  "section" ws? n:section-name (
+      ws? ',' ws? f:section-flags ws? ',' ws? t:section-type
+      {$$.section = (DirSection){.kind=ASM_DIR_SECTION, .name=n.charptr, .flags=f.charptr, .type=t.i64}; }
+    | ws? ',' ws? f:section-flags
+      {$$.section = (DirSection){.kind=ASM_DIR_SECTION, .name=n.charptr, .flags=f.charptr, .type=SHT_PROGBITS}; }
+    | 
+      {$$.section = (DirSection){.kind=ASM_DIR_SECTION, .name=n.charptr, .flags="", .type=SHT_PROGBITS}; }
+  )
+
+section-name = <[.a-zA-Z0-9\-]+> { $$.charptr = xstrdup(yytext); }
+section-flags = '"' <[awx]*> '"' { $$.charptr = xstrdup(yytext); }
+section-type =
+    "@nobits" { $$.i64 = SHT_NOBITS; }
+  | "@progbits" { $$.i64 = SHT_PROGBITS; }
 
 label = 
   i:ident ':'
diff --git a/main.c b/main.c
index 5914994..8e3da68 100644
--- a/main.c
+++ b/main.c
@@ -78,6 +78,19 @@ static Section *newsection() {
   return s;
 }
 
+static Section *getsection(const char *name) {
+  size_t i;
+  Section *s;
+
+  for (i = 0; i < nsections; i++) {
+    if (strcmp(secname(&sections[i]), name) == 0)
+      return &sections[i];
+  }
+  s = newsection();
+  s->hdr.sh_name = elfstr(shstrtab, name);
+  return s;
+}
+
 static void initsections(void) {
   Elf64_Sym elfsym;
 
@@ -530,6 +543,32 @@ static void assemble(void) {
       sym = getsym(v->globl.name);
       sym->global = 1;
       break;
+    case ASM_DIR_SECTION: {
+      size_t i;
+      const char *fp;
+      Section *s;
+
+      s = getsection(v->section.name);
+      s->hdr.sh_type = v->section.type;
+      fp = v->section.flags;
+      while (fp && *fp) {
+        switch (*(fp++)) {
+        case 'a':
+          s->hdr.sh_flags |= SHF_ALLOC;
+          break;
+        case 'w':
+          s->hdr.sh_flags |= SHF_WRITE;
+          break;
+        case 'x':
+          s->hdr.sh_flags |= SHF_EXECINSTR;
+          break;
+        default:
+          unreachable();
+        }
+      }
+      cursection = s;
+      break;
+    }
     case ASM_DIR_DATA:
       cursection = data;
       break;
diff --git a/minias.h b/minias.h
index 68df579..78d478a 100644
--- a/minias.h
+++ b/minias.h
@@ -49,6 +49,7 @@ typedef enum {
   ASM_MEMARG,
   // Directives
   ASM_DIR_GLOBL,
+  ASM_DIR_SECTION,
   ASM_DIR_ASCII,
   ASM_DIR_ASCIIZ,
   ASM_DIR_DATA,
@@ -164,6 +165,13 @@ typedef struct {
 
 typedef struct {
   AsmKind kind;
+  const char *name;
+  const char *flags;
+  int type;
+} DirSection;
+
+typedef struct {
+  AsmKind kind;
   uint8_t b;
 } Byte;
 
@@ -231,6 +239,7 @@ union Parsev {
   AsmKind kind;
   Label label;
   Globl globl;
+  DirSection section;
   Balign balign;
   Ascii ascii;
   Asciiz asciiz;
@@ -244,6 +253,9 @@ union Parsev {
   Ident ident;
   Number number;
   String string;
+  // Temporary values.
+  const char *charptr;
+  int64_t i64;
 };
 
 typedef struct AsmLine AsmLine;