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feat : enable FPU in UCOS
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This change enable the saving and restoring of FPU
registers during context switch.

[ISDK-60](https://iontra.atlassian.net/browse/ISDK-60)

Signed-off-by: Gaurav <[email protected]>
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@iontra-gaurav
iontra-gaurav committed May 16, 2024
1 parent 5be7f3b commit 845c86b
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Showing 2 changed files with 115 additions and 10 deletions.
118 changes: 110 additions & 8 deletions Ports/RISC-V/RV32/GCC/os_cpu_a.S
View file
Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,6 @@
# For : RISC-V RV32
# Toolchain : GNU C Compiler
#********************************************************************************************************
# Note(s) : Hardware FP is not supported.
#********************************************************************************************************

#********************************************************************************************************
Expand Down Expand Up @@ -71,7 +70,7 @@
# a) Call OSTaskSwHook() then,
# b) Set OSRunning to TRUE,
# c) Set OSTCBHighRdyPtr->StkPtr = SP
# d) Restore x1-x31; There is no need to restore x0 since it is always zero.
# d) Restore x1-x31 and f0-f31; There is no need to restore x0 since it is always zero.
# e) Enable interrupts (tasks will run with interrupts enabled).
# f) Switch to highest priority task.
#********************************************************************************************************
Expand Down Expand Up @@ -108,7 +107,7 @@ OSStartHighRdy:
# value stored in t0 is stored into mepc
csrw mepc, t0

# Restore x1 to x31 registers
# Restore x1 to x31 registers (base registers)
# load word from memory addres [(0 * 4) + sp] into ra register
lw ra, 0 * 4(sp)
lw t0, 4 * 4(sp)
Expand Down Expand Up @@ -139,9 +138,43 @@ OSStartHighRdy:
lw t5, 29 * 4(sp)
lw t6, 30 * 4(sp)

#Restore f0 to f31 registers (FP registers)
flw f0, 32 * 4(sp)
flw f1, 33 * 4(sp)
flw f2, 34 * 4(sp)
flw f3, 35 * 4(sp)
flw f4, 36 * 4(sp)
flw f5, 37 * 4(sp)
flw f6, 38 * 4(sp)
flw f7, 39 * 4(sp)
flw f8, 40 * 4(sp)
flw f9, 41 * 4(sp)
flw f10, 42 * 4(sp)
flw f11, 43 * 4(sp)
flw f12, 44 * 4(sp)
flw f13, 45 * 4(sp)
flw f14, 46 * 4(sp)
flw f15, 47 * 4(sp)
flw f16, 48 * 4(sp)
flw f17, 49 * 4(sp)
flw f18, 50 * 4(sp)
flw f19, 51 * 4(sp)
flw f20, 52 * 4(sp)
flw f21, 53 * 4(sp)
flw f22, 54 * 4(sp)
flw f23, 55 * 4(sp)
flw f24, 56 * 4(sp)
flw f25, 57 * 4(sp)
flw f26, 58 * 4(sp)
flw f27, 59 * 4(sp)
flw f28, 60 * 4(sp)
flw f29, 61 * 4(sp)
flw f30, 62 * 4(sp)
flw f31, 63 * 4(sp)

# Compensate for the stack pointer
# sp = sp + 32 * 4
addi sp, sp, 32 * 4
# sp = sp + 64 * 4
addi sp, sp, 64 * 4

# Use register t6 to jump to HIGHEST priority
csrr t6, mepc
Expand Down Expand Up @@ -176,7 +209,7 @@ OSCtxSw:
.align 8
ucos_intr_exception_handler:
# save regs to current sp
addi sp, sp, -4*32
addi sp, sp, -4*64
# store contents of register ra into memory [(0 * 4) + sp]
sw ra, 0 * 4(sp)
sw t0, 4 * 4(sp)
Expand Down Expand Up @@ -207,6 +240,40 @@ ucos_intr_exception_handler:
sw t5, 29 * 4(sp)
sw t6, 30 * 4(sp)

# save f0 to f31 registers (FPU registers)
fsw f0, 32 * 4(sp)
fsw f1, 33 * 4(sp)
fsw f2, 34 * 4(sp)
fsw f3, 35 * 4(sp)
fsw f4, 36 * 4(sp)
fsw f5, 37 * 4(sp)
fsw f6, 38 * 4(sp)
fsw f7, 39 * 4(sp)
fsw f8, 40 * 4(sp)
fsw f9, 41 * 4(sp)
fsw f10, 42 * 4(sp)
fsw f11, 43 * 4(sp)
fsw f12, 44 * 4(sp)
fsw f13, 45 * 4(sp)
fsw f14, 46 * 4(sp)
fsw f15, 47 * 4(sp)
fsw f16, 48 * 4(sp)
fsw f17, 49 * 4(sp)
fsw f18, 50 * 4(sp)
fsw f19, 51 * 4(sp)
fsw f20, 52 * 4(sp)
fsw f21, 53 * 4(sp)
fsw f22, 54 * 4(sp)
fsw f23, 55 * 4(sp)
fsw f24, 56 * 4(sp)
fsw f25, 57 * 4(sp)
fsw f26, 58 * 4(sp)
fsw f27, 59 * 4(sp)
fsw f28, 60 * 4(sp)
fsw f29, 61 * 4(sp)
fsw f30, 62 * 4(sp)
fsw f31, 63 * 4(sp)

# If it is a ecall, do not add 4 in mepc
# otherwise add 4 in mepc
li t1, ARCH_CPU_MCAUSE_CAUSE_MASK
Expand Down Expand Up @@ -262,7 +329,8 @@ run_ecall_handler:
# c) Get current ready thread TCB, OSTCBCurPtr = OSTCBHighRdyPtr;
# d) Get new process SP from TCB, SP = OSTCBHighRdyPtr->StkPtr;
# e) Retrieve the address at which exception happened.
# f) Restore x1-x31 from new process stack; x0 is always zero.
# f) Restore x1-x31(base registers) and f0-f31(FP registers)
# from new process stack; x0 is always zero.
# g) set MPIE = 1 to enable interrupt before returning.
# h) Perform exception return which will restore remaining context.
#
Expand Down Expand Up @@ -321,8 +389,42 @@ Software_IRQHandler:
lw t5, 29 * 4(sp)
lw t6, 30 * 4(sp)

# Restore f0 to f31 registers (FPU registers)
flw f0, 32 * 4(sp)
flw f1, 33 * 4(sp)
flw f2, 34 * 4(sp)
flw f3, 35 * 4(sp)
flw f4, 36 * 4(sp)
flw f5, 37 * 4(sp)
flw f6, 38 * 4(sp)
flw f7, 39 * 4(sp)
flw f8, 40 * 4(sp)
flw f9, 41 * 4(sp)
flw f10, 42 * 4(sp)
flw f11, 43 * 4(sp)
flw f12, 44 * 4(sp)
flw f13, 45 * 4(sp)
flw f14, 46 * 4(sp)
flw f15, 47 * 4(sp)
flw f16, 48 * 4(sp)
flw f17, 49 * 4(sp)
flw f18, 50 * 4(sp)
flw f19, 51 * 4(sp)
flw f20, 52 * 4(sp)
flw f21, 53 * 4(sp)
flw f22, 54 * 4(sp)
flw f23, 55 * 4(sp)
flw f24, 56 * 4(sp)
flw f25, 57 * 4(sp)
flw f26, 58 * 4(sp)
flw f27, 59 * 4(sp)
flw f28, 60 * 4(sp)
flw f29, 61 * 4(sp)
flw f30, 62 * 4(sp)
flw f31, 63 * 4(sp)

# Compensate for the stack pointer
addi sp, sp, 4 * 32
addi sp, sp, 4 * 64

# Exception return will restore remaining context
# set MPIE = 1
Expand Down
7 changes: 5 additions & 2 deletions Ports/RISC-V/RV32/GCC/os_cpu_c.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -306,8 +306,12 @@ CPU_STK *OSTaskStkInit (OS_TASK_PTR p_task,
p_stk = &p_stk_base[stk_size]; /* Load stack pointer and align it to 16-bytes */
p_stk = (CPU_STK *)((CPU_STK)(p_stk) & 0xFFFFFFF0u);

/* make space for floating point registers */
for(int i = 0; i < 32; i++) {
*(--p_stk) = (CPU_STK)0;
}
/* make space for base registers */
*(--p_stk) = (CPU_STK) p_task; /* Entry Point */

*(--p_stk) = (CPU_STK) 0x31313131uL; /* t6 */
*(--p_stk) = (CPU_STK) 0x30303030uL; /* t5 */
*(--p_stk) = (CPU_STK) 0x29292929uL; /* t4 */
Expand Down Expand Up @@ -344,7 +348,6 @@ CPU_STK *OSTaskStkInit (OS_TASK_PTR p_task,
*(--p_stk) = (CPU_STK) 0x03030303uL; /* gp: Global pointer */
*(--p_stk) = (CPU_STK) 0x02020202uL; /* sp: Stack pointer */
*(--p_stk) = (CPU_STK) OS_TaskReturn; /* ra: return address */

return (p_stk);
}

Expand Down

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