From ccc04526f14764d856ad37b1f517308fccf886a6 Mon Sep 17 00:00:00 2001
From: Jacques Comeaux <jacquesrcomeaux@protonmail.com>
Date: Wed, 21 Aug 2024 03:18:35 -0500
Subject: Add label and opcode parsers

---
 newasm/label.s | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 newasm/label.s

(limited to 'newasm/label.s')

diff --git a/newasm/label.s b/newasm/label.s
new file mode 100644
index 0000000..af2f641
--- /dev/null
+++ b/newasm/label.s
@@ -0,0 +1,30 @@
+.syntax unified
+.cpu cortex-m0plus
+.thumb
+
+.type label, %function
+.global label
+
+// 1 unexpected begin char
+// 2 doesn't end with colon
+
+// R1 input buffer
+// R2 output buffer
+
+label:    PUSH    {LR}
+          LDRB    R0, [R1]    // get a char
+          CMP     R0, 0x61    // a
+          BLO     1f
+          CMP     R0, 0x7A    // z
+          BLS     2f
+1:        MOVS    R0, #1      // return code 1 (expected lowercase)
+          POP     {PC}
+2:        BL      symbol
+          LDRB    R0, [R1]    // get a char
+          CMP     R0, ':      // colon
+          BEQ     3f
+          MOVS    R0, #2      // return code 2 (expected colon)
+          POP     {PC}
+3:        ADDS    R1, 1       // consume the colon
+          MOVS    R0, #0      // return code 0 (success)
+          POP     {PC}
-- 
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