[sw] Unsigned Comparisons in Address Loops
Both CRTs use signed comparisons for their data clearing/loading loops.
However, these loops use addresses as their induction variables, and
addresses are unsigned, so the comparisons must be unsigned. This was
noticed by @alphan in the review of #2991, and this change applies it to
the existing CRTs.
Signed-off-by: Sam Elliott <selliott@lowrisc.org>
diff --git a/sw/device/boot_rom/rom_crt.S b/sw/device/boot_rom/rom_crt.S
index 33c16e1..68e1a0a 100644
--- a/sw/device/boot_rom/rom_crt.S
+++ b/sw/device/boot_rom/rom_crt.S
@@ -76,13 +76,13 @@
//
// We use `t0` and `t1` to represent the start and end pointers
// of `.bss`.
- la t0, _bss_start
- la t1, _bss_end
- bge t0, t1, bss_zero_loop_end
+ la t0, _bss_start
+ la t1, _bss_end
+ bgeu t0, t1, bss_zero_loop_end
bss_zero_loop:
sw zero, 0(t0)
addi t0, t0, 0x4
- blt t0, t1, bss_zero_loop
+ bltu t0, t1, bss_zero_loop
bss_zero_loop_end:
// Zero out the stack
@@ -90,13 +90,13 @@
// We use `t0` and `t1` to represent the start and end pointers of the stack.
// As the stack grows downwards and we zero going forwards the start pointer
// starts as _stack_end and the end pointer at _stack_start
- la t0, _stack_end
- la t1, _stack_start
- bge t0, t1, stack_zero_loop_end
+ la t0, _stack_end
+ la t1, _stack_start
+ bgeu t0, t1, stack_zero_loop_end
stack_zero_loop:
sw zero, 0(t0)
addi t0, t0, 0x4
- blt t0, t1, stack_zero_loop
+ bltu t0, t1, stack_zero_loop
stack_zero_loop_end:
// Initialize the `.data` segment from the `.idata` segment.
@@ -105,16 +105,16 @@
// of `.data`, `t2` to represent the start pointer of `.idata`
// (which has the same length as `.data`) and `t3` is a scratch
// register for the copy.
- la t0, _data_start
- la t1, _data_end
- la t2, _data_init_start
- bge t0, t1, data_copy_loop_end
+ la t0, _data_start
+ la t1, _data_end
+ la t2, _data_init_start
+ bgeu t0, t1, data_copy_loop_end
data_copy_loop:
lw t3, 0(t2)
sw t3, 0(t0)
addi t0, t0, 0x4
addi t2, t2, 0x4
- blt t0, t1, data_copy_loop
+ bltu t0, t1, data_copy_loop
data_copy_loop_end:
// Re-clobber all of the registers from above.
diff --git a/sw/device/exts/common/flash_crt.S b/sw/device/exts/common/flash_crt.S
index 11faeea..aba810e 100644
--- a/sw/device/exts/common/flash_crt.S
+++ b/sw/device/exts/common/flash_crt.S
@@ -42,13 +42,13 @@
//
// We use `t0` and `t1` to represent the start and end pointers
// of `.bss`.
- la t0, _bss_start
- la t1, _bss_end
- bge t0, t1, bss_zero_loop_end
+ la t0, _bss_start
+ la t1, _bss_end
+ bgeu t0, t1, bss_zero_loop_end
bss_zero_loop:
sw zero, 0(t0)
addi t0, t0, 0x4
- blt t0, t1, bss_zero_loop
+ bltu t0, t1, bss_zero_loop
bss_zero_loop_end:
// Zero out the stack
@@ -56,13 +56,13 @@
// We use `t0` and `t1` to represent the start and end pointers of the stack.
// As the stack grows downwards and we zero going forwards the start pointer
// starts as _stack_end and the end pointer at _stack_start.
- la t0, _stack_end
- la t1, _stack_start
- bge t0, t1, stack_zero_loop_end
+ la t0, _stack_end
+ la t1, _stack_start
+ bgeu t0, t1, stack_zero_loop_end
stack_zero_loop:
sw zero, 0(t0)
addi t0, t0, 0x4
- blt t0, t1, stack_zero_loop
+ bltu t0, t1, stack_zero_loop
stack_zero_loop_end:
// Initialize the `.data` segment from the `.idata` segment.
@@ -71,16 +71,16 @@
// of `.data`, `t2` to represent the start pointer of `.idata`
// (which has the same length as `.data`) and `t3` is a scratch
// register for the copy.
- la t0, _data_start
- la t1, _data_end
- la t2, _data_init_start
- bge t0, t1, data_copy_loop_end
+ la t0, _data_start
+ la t1, _data_end
+ la t2, _data_init_start
+ bgeu t0, t1, data_copy_loop_end
data_copy_loop:
lw t3, 0(t2)
sw t3, 0(t0)
addi t0, t0, 0x4
addi t2, t2, 0x4
- blt t0, t1, data_copy_loop
+ bltu t0, t1, data_copy_loop
data_copy_loop_end:
// Jump into the C program entry point. This is your standard
