From a4a7080dee359ca95f09d91d68d1d8c4a1f59cd6 Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Sun, 27 Jul 2025 22:59:18 -0400
Subject: oasm: Introduce AND mnemonic

Implement mnemonic for the AND instruction:

--
and x1, #7   ! x1 = x1 & 7
--

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 usr.bin/oasm/emit.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)

(limited to 'usr.bin/oasm/emit.c')

diff --git a/usr.bin/oasm/emit.c b/usr.bin/oasm/emit.c
index 6b17eab..ea14cce 100644
--- a/usr.bin/oasm/emit.c
+++ b/usr.bin/oasm/emit.c
@@ -377,6 +377,60 @@ emit_encode_nop(struct emit_state *state, struct oasm_token *tok)
     return TAILQ_NEXT(tok, link);
 }
 
+/*
+ * Encode a bitwise instruction:
+ *
+ * and r, r/imm
+ * or r, r/imm
+ * xor r, r/imm
+ */
+static struct oasm_token *
+emit_encode_bitw(struct emit_state *state, struct oasm_token *tok)
+{
+    inst_t curinst;
+    imm_t imm;
+    reg_t rd;
+    uint8_t opcode = OSMX64_AND;
+    char *inst_str = "and";
+
+    /* Next token should be a register */
+    tok = TAILQ_NEXT(tok, link);
+    if (tok == NULL) {
+        oasm_err("[emit error]: expected register for '%s'\n", inst_str);
+        return NULL;
+    }
+    if (!tok_is_xreg(tok->type)) {
+        oasm_err("[emit error]: bad register for '%s'\n", inst_str);
+        return NULL;
+    }
+
+    rd = ir_to_reg(tok->type);
+    tok = TAILQ_NEXT(tok, link);
+    if (tok == NULL) {
+        oasm_err("[emit error]: missing operand in '%s'\n", inst_str);
+        return NULL;
+    }
+
+    /*
+     * Check that the next token is an immediate
+     * value.
+     *
+     * TODO: Allow a register operand to be passed
+     *       to these instructions.
+     */
+    if (tok->type != TT_IMM) {
+        oasm_err("[emit error]: expected <imm> for '%s'\n", inst_str);
+        return NULL;
+    }
+
+    imm = tok->imm;
+    curinst.opcode = opcode;
+    curinst.rd = rd;
+    curinst.imm = imm;
+    emit_bytes(state, &curinst, sizeof(curinst));
+    return TAILQ_NEXT(tok, link);
+}
+
 int
 emit_osmx64(struct emit_state *state, struct oasm_token *tp)
 {
@@ -464,6 +518,9 @@ emit_process(struct oasm_state *oasm, struct emit_state *emit)
         case TT_DIV:
             curtok = emit_encode_arith(emit, curtok);
             break;
+        case TT_AND:
+            curtok = emit_encode_bitw(emit, curtok);
+            break;
         case TT_BR:
             curtok = emit_encode_br(emit, curtok);
             break;
-- 
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