Add parsers for basic instruction typesHEADmaster

1 files changed, 27 insertions, 0 deletions

diff --git a/newasm/imm.s b/newasm/imm.s
new file mode 100644
index 0000000..f6c7266
--- /dev/null
+++ b/newasm/imm.s
@@ -0,0 +1,27 @@
+.syntax unified
+.cpu cortex-m0plus
+.thumb
+
+.type imm, %function
+.global imm
+
+// R1 instruction under construction
+// R3 immediate width
+// R4 input buffer
+
+imm:      PUSH    {LR}
+          PUSH    {R3}
+          BL      immediate
+          POP     {R3}
+          BNE     exit
+          MOVS    R0, 1
+          LSLS    R0, R3
+          CMP     R2, R0
+          BLO     fine
+          MOVS    R0, 0x0A    // return code 0A (immediate value too large)
+          POP     {PC}
+fine:     ORRS    R1, R2      // fill in imm
+          MOVS    R0, 0       // return code 0 (success)
+exit:     POP     {PC}
+bad_reg:  MOVS    R0, 8       // return code 8 (invalid register for this register position)
+          POP     {PC}