oasm: Add encoding for BR instruction

Signed-off-by: Ian Moffett <ian@osmora.org>

5 files changed, 71 insertions, 0 deletions

diff --git a/usr.bin/oasm/emit.c b/usr.bin/oasm/emit.c
index 0e8ad4e..eb38779 100644
--- a/usr.bin/oasm/emit.c
+++ b/usr.bin/oasm/emit.c
@@ -257,6 +257,45 @@ emit_encode_hlt(struct emit_state *state, struct oasm_token *tok)
     return TAILQ_NEXT(tok, link);
 }
 
+/*
+ * Encode a BR instruction
+ *
+ * br [r]
+ *
+ * Returns the next token on success,
+ * otherwise NULL.
+ */
+static struct oasm_token *
+emit_encode_br(struct emit_state *state, struct oasm_token *tok)
+{
+    inst_t curinst;
+    reg_t rd;
+    uint8_t opcode = OSMX64_BR;
+    char *inst_str = "br";
+
+    /* Grab the register */
+    tok = TAILQ_NEXT(tok, link);
+    if (tok == NULL) {
+        return NULL;
+    }
+    if (!tok_is_xreg(tok->type)) {
+        oasm_err("[emit error]: expected register in '%s'\n", inst_str);
+        return NULL;
+    }
+
+    rd = ir_to_reg(tok->type);
+    if (rd == OSMX64_R_BAD) {
+        oasm_err("[emit error]: got bad in register in '%s'\n", inst_str);
+        return NULL;
+    }
+
+    curinst.opcode = opcode;
+    curinst.rd = rd;
+    curinst.unused = 0;
+    emit_bytes(state, &curinst, sizeof(curinst));
+    return TAILQ_NEXT(tok, link);
+}
+
 int
 emit_osmx64(struct emit_state *state, struct oasm_token *tp)
 {
@@ -341,6 +380,9 @@ emit_process(struct oasm_state *oasm, struct emit_state *emit)
         case TT_DIV:
             curtok = emit_encode_arith(emit, curtok);
             break;
+        case TT_BR:
+            curtok = emit_encode_br(emit, curtok);
+            break;
         case TT_HLT:
             curtok = emit_encode_hlt(emit, curtok);
             break;
diff --git a/usr.bin/oasm/include/oasm/emit.h b/usr.bin/oasm/include/oasm/emit.h
index d289adb..dab63d0 100644
--- a/usr.bin/oasm/include/oasm/emit.h
+++ b/usr.bin/oasm/include/oasm/emit.h
@@ -61,6 +61,7 @@
 #define OSMX64_SRL      0x12    /* Shift right logical operation */
 #define OSMX64_MOV_IMM  0x13    /* Data move operation from IMM */
 #define OSMX64_HLT      0x14    /* Halt the processor */
+#define OSMX64_BR       0x15    /* Branch */
 
 /*
  * OSMX64 register definitions
diff --git a/usr.bin/oasm/include/oasm/lex.h b/usr.bin/oasm/include/oasm/lex.h
index 6ffaf79..62183e0 100644
--- a/usr.bin/oasm/include/oasm/lex.h
+++ b/usr.bin/oasm/include/oasm/lex.h
@@ -96,6 +96,7 @@ typedef enum {
     TT_MUL,         /* 'mul' */
     TT_DIV,         /* 'div' */
     TT_HLT,         /* 'hlt' */
+    TT_BR,          /* 'br'  */
 
     /* Register ops */
     TT_MOV,         /* 'mov' */
diff --git a/usr.bin/oasm/lex.c b/usr.bin/oasm/lex.c
index 7b78d54..3ca9e8d 100644
--- a/usr.bin/oasm/lex.c
+++ b/usr.bin/oasm/lex.c
@@ -47,6 +47,7 @@ static char putback = '\0';
 #define S_IMN_INC  "inc"
 #define S_IMN_DEC  "dec"
 #define S_IMN_HLT  "hlt"
+#define S_IMN_BR   "br"
 
 /*
  * Returns 0 if a char is counted as a
@@ -190,6 +191,19 @@ token_arith(char *p)
     return TT_UNKNOWN;
 }
 
+/*
+ * Control flow instructions
+ */
+static tt_t
+token_cfi(char *p)
+{
+    if (strcmp(p, S_IMN_BR) == 0) {
+        return TT_BR;
+    }
+
+    return TT_UNKNOWN;
+}
+
 static tt_t
 token_xreg(char *p)
 {
@@ -293,6 +307,13 @@ lex_tok(struct oasm_state *state, struct oasm_token *ttp)
             return 0;
         }
 
+        /* Control flow instruction? */
+        if ((tok = token_cfi(p)) != TT_UNKNOWN) {
+            ttp->type = tok;
+            ttp->raw = p;
+            return 0;
+        }
+
         /* Register? */
         if ((tok = token_reg(p)) != TT_UNKNOWN) {
             ttp->is_reg = 1;
diff --git a/usr.bin/oasm/parse.c b/usr.bin/oasm/parse.c
index 9a4dd0e..e288d6e 100644
--- a/usr.bin/oasm/parse.c
+++ b/usr.bin/oasm/parse.c
@@ -43,6 +43,7 @@ static const char *tokstr[] = {
     [ TT_MUL ] = "mul",
     [ TT_DIV ] = "div",
     [ TT_HLT ] = "hlt",
+    [ TT_BR  ] = "br",
     [ TT_COMMA ] = ",",
     [ TT_INC ] = "inc",
     [ TT_DEC ] = "dec",
@@ -112,6 +113,7 @@ parse_reg(struct oasm_state *state, struct oasm_token *tok)
     case TT_SUB:
     case TT_MUL:
     case TT_DIV:
+    case TT_BR:
         state->last = tok->type;
         break;
     default:
@@ -144,6 +146,10 @@ parse_tok(struct oasm_state *state, struct oasm_token *tok)
     int error;
 
     switch (tok->type) {
+    case TT_BR:
+        state->last = tok->type;
+        emit_osmx64(&emit_state, tok);
+        break;
     case TT_HLT:
         state->last = tok->type;
         emit_osmx64(&emit_state, tok);