From ccc04526f14764d856ad37b1f517308fccf886a6 Mon Sep 17 00:00:00 2001 From: Jacques Comeaux Date: Wed, 21 Aug 2024 03:18:35 -0500 Subject: Add label and opcode parsers --- newasm/opcode.s | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 newasm/opcode.s (limited to 'newasm/opcode.s') diff --git a/newasm/opcode.s b/newasm/opcode.s new file mode 100644 index 0000000..71a5201 --- /dev/null +++ b/newasm/opcode.s @@ -0,0 +1,40 @@ +.syntax unified +.cpu cortex-m0plus +.thumb + +.type opcode, %function +.global opcode + +// 1 unexpected first char + +// R1 input buffer +// R2 output buffer + +opcode: PUSH {LR} + LDRB R0, [R1] // get a char + CMP R0, 0x41 // A + BLO 1f + CMP R0, 0x5A // Z + BLS 2f +1: MOVS R0, #1 // unexpected char + POP {PC} +2: ADDS R1, 1 // consume the character + STRB R0, [R2] // store in temp buffer + ADDS R2, 1 // advance temp buffer pointer + LDRB R0, [R1] // get another character + BL goodchar // check if valid symbol char + BEQ 2b // if so keep getting chars + MOVS R0, #0 // return code success + STRB R0, [R2] // write null byte + POP {PC} + +goodchar: CMP R0, '0 + BLO bad + CMP R0, '9 + BLS good + CMP R0, 'A + BLO bad + CMP R0, 'Z + BHI bad +good: CMP R0, R0 +bad: BX LR -- cgit v1.2.3