From 7388c270069c2d1418539bca1d2789a6d468ecc2 Mon Sep 17 00:00:00 2001
From: Jacques Comeaux <jacquesrcomeaux@protonmail.com>
Date: Mon, 20 May 2024 23:19:14 -0500
Subject: Make shared object for setup routines

---
 assembler/Makefile         | 21 +++++++++++++++
 assembler/main.s           | 17 ++++++++++++
 assembler/pico_ram_only.ld | 13 ++++++++++
 assembler/uart.s           | 65 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 116 insertions(+)
 create mode 100644 assembler/Makefile
 create mode 100644 assembler/main.s
 create mode 100644 assembler/pico_ram_only.ld
 create mode 100644 assembler/uart.s

(limited to 'assembler')

diff --git a/assembler/Makefile b/assembler/Makefile
new file mode 100644
index 0000000..96b7971
--- /dev/null
+++ b/assembler/Makefile
@@ -0,0 +1,21 @@
+all: build
+
+build: assemble.uf2
+
+assemble.uf2: assemble.elf
+	../elf/elf2uf2 assemble.elf assemble.uf2
+
+objects = main.o uart.o assemble.o register.o octal.o opcode.o
+
+assemble.elf: $(objects)
+	arm-none-eabi-ld -T pico_ram_only.ld -o assemble.elf $(objects) ../setup/setup.so
+
+$(objects): %.o: %.s
+	arm-none-eabi-as -o $@ $<
+
+clean:
+	rm assemble.elf assemble.uf2 *.o
+
+flash: assemble.uf2
+	[ -h /dev/disk/by-label/RPI-RP2 ] || sleep 2s
+	cat assemble.uf2 > /dev/disk/by-label/RPI-RP2
diff --git a/assembler/main.s b/assembler/main.s
new file mode 100644
index 0000000..9a7fd89
--- /dev/null
+++ b/assembler/main.s
@@ -0,0 +1,17 @@
+.syntax unified
+.cpu cortex-m0plus
+.thumb
+
+.type main, %function
+.global main
+
+main:
+  bl start_xosc
+  bl setup_clocks
+  bl setup_gpio
+  bl setup_uart
+1:
+  bl assemble
+  movs r0, r6
+  bl send_hex
+  b 1b
diff --git a/assembler/pico_ram_only.ld b/assembler/pico_ram_only.ld
new file mode 100644
index 0000000..eb2450e
--- /dev/null
+++ b/assembler/pico_ram_only.ld
@@ -0,0 +1,13 @@
+ENTRY(main)
+
+MEMORY {
+  FLASH(rx) : ORIGIN = 0x10000000, LENGTH = 2M
+  SRAM(rwx) : ORIGIN = 0x20000000, LENGTH = 264K
+}
+
+SECTIONS {
+  .text : {
+    *(.text)
+    . = ALIGN(4);
+  } > SRAM
+}
diff --git a/assembler/uart.s b/assembler/uart.s
new file mode 100644
index 0000000..b845c8b
--- /dev/null
+++ b/assembler/uart.s
@@ -0,0 +1,65 @@
+.syntax unified
+.cpu cortex-m0plus
+.thumb
+
+.equ UART0_BASE, 0x40034000
+.equ UARTDR_OFST,     0x00
+.equ UARTFR_OFST,     0x18
+
+.type uart_send, %function
+.global uart_send
+
+uart_send:
+  ldr r1, =UART0_BASE
+  movs r3, 0b1 << 5 // TX FIFO full
+1:
+  ldr r2, [r1, UARTFR_OFST]
+  tst r2, r3
+  bne 1b
+  strb r0, [r1, UARTDR_OFST]
+  bx lr
+
+.type uart_recv, %function
+.global uart_recv
+
+uart_recv:
+  ldr r1, =UART0_BASE
+  movs r3, 0b1 << 4 // RX FIFO empty
+1:
+  ldr r2, [r1, UARTFR_OFST]
+  tst r2, r3
+  bne 1b
+  ldrb r0, [r1, UARTDR_OFST]
+  bx lr
+
+.type send_hex, %function
+.global send_hex
+
+send_hex:
+  push {lr}
+  movs r4, r0
+  movs r0, '0
+  bl uart_send
+  movs r0, 'x
+  bl uart_send
+  movs r5, 8 // eight nibbles in a word
+0:
+  movs r0, 28 // rotate left 4
+  rors r4, r0
+  movs r0, 0xF // lowest nibble mask
+  ands r0, r4
+  cmp r0, 0x9 // number or letter?
+  bhi 1f
+  adds r0, '0
+  b 2f
+1:
+  adds r0, ('A - 0xA)
+2:
+  bl uart_send
+  subs r5, 1
+  bne 0b
+  movs r0, '\r
+  bl uart_send
+  movs r0, '\n
+  bl uart_send
+  pop {pc}
-- 
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